Texas Hunting Forum

POI of heavier vs. lighter bullets

Posted By: onlysmith&wesson

POI of heavier vs. lighter bullets - 01/25/21 05:58 PM

Same rifle, shooting 129 gr. SST at 2950 fps vs 143 gr. ELDX at 2700 fps. 100 yard zero with the SST's, tried a few of the ELD-X's and poi was like 2" higher. 20", 1-8 WC AR-10 off a bipod.

Who wants to tell me why?

I like this answer: "Lighter bullets at higher velocity spend less time in the barrel. Heavier bullets are slower and spend more time in a barrel that's recoiling upwards for a higher POI than lighter"
Posted By: redchevy

Re: POI of heavier vs. lighter bullets - 01/25/21 06:04 PM

Who knows, I would attribute it to variations in harmonics or just how that barrel handles that bullet.

I have about 7 different loads that all shot to the same point out of my 270 win ranging from 90 grain hollow points going 3500 fps to 150 grain partitions going 2725 fps and 110 grain reduced ammo going 2500 fps. I shot them all at the range same day and wound up with a ragged hole about the size of a 50 cent piece at 100 yards after about 20 shots.
Posted By: patriot07

Re: POI of heavier vs. lighter bullets - 01/25/21 06:07 PM

Originally Posted by redchevy
Who knows, I would attribute it to variations in harmonics or just how that barrel handles that bullet.
In my experience, this is the correct answer
Posted By: HicksHunter

Re: POI of heavier vs. lighter bullets - 01/25/21 06:07 PM

Contrary to popular belief, it has nothing to do with the gun's recoil. The bullet is already long gone by the time the gun is moving backwards. This is even true with slow-moving pistol calibers.

The trajectory of the bullet changes with velocity. You can check this with any ballistic calculator. A faster bullet will have traveled farther forwards in a given period of time, and thus will reach the apex of its travel farther away. Taken at any distance before then, it will appear to hit lower on the target than a slower bullet.
Posted By: redchevy

Re: POI of heavier vs. lighter bullets - 01/25/21 06:15 PM

Originally Posted by HicksHunter
Contrary to popular belief, it has nothing to do with the gun's recoil. The bullet is already long gone by the time the gun is moving backwards. This is even true with slow-moving pistol calibers.

The trajectory of the bullet changes with velocity. You can check this with any ballistic calculator. A faster bullet will have traveled farther forwards in a given period of time, and thus will reach the apex of its travel farther away. Taken at any distance before then, it will appear to hit lower on the target than a slower bullet.

Im not sure i believe that either.

If you change your grip on a pistol/rifle from loose to trying to keep the rifle from moving at all costs it will change the point of impact.
Posted By: J.G.

Re: POI of heavier vs. lighter bullets - 01/25/21 06:19 PM

Originally Posted by patriot07
Originally Posted by redchevy
Who knows, I would attribute it to variations in harmonics or just how that barrel handles that bullet.
In my experience, this is the correct answer


Yup. Harmonics

And this is what hand loaders handload for. Getting the right charge to work with the barrel's harmonics for "X" bullet. Looks like this rifle just agrees with the 143's, if they are heavier and hitting higher. Bullet probably leaves the barrel at the apex of the sine wave. All is well, as long as it hits consistently.
Posted By: onlysmith&wesson

Re: POI of heavier vs. lighter bullets - 01/25/21 06:37 PM

Originally Posted by HicksHunter
Contrary to popular belief, it has nothing to do with the gun's recoil. The bullet is already long gone by the time the gun is moving backwards. This is even true with slow-moving pistol calibers.

The trajectory of the bullet changes with velocity. You can check this with any ballistic calculator. A faster bullet will have traveled farther forwards in a given period of time, and thus will reach the apex of its travel farther away. Taken at any distance before then, it will appear to hit lower on the target than a slower bullet.

Interesting. I'd like to see a trajectory line for these two, side by side. That would prove it.

What ever it is doing, it does it exactly the same every time with the SST's. I shot it for drop a couple of weeks age at 200, 300 and 400 yards. It worked on a live target the next day at 280 yards. Held the 8" I had from the day before at 300, dead pig.
Posted By: GLC

Re: POI of heavier vs. lighter bullets - 01/25/21 07:45 PM

Working up a load with using the same manufacturer, exact model and grain of bullet, you will find that one load may be 2" high and to the right and then another load be 2" low and to the left. What you are doing above is changing grain and bullet styles also , no telling how many different ways it will fly.
Posted By: BOBO the Clown

Re: POI of heavier vs. lighter bullets - 01/25/21 07:55 PM

Originally Posted by HicksHunter
Contrary to popular belief, it has nothing to do with the gun's recoil. The bullet is already long gone by the time the gun is moving backwards. This is even true with slow-moving pistol calibers.

The trajectory of the bullet changes with velocity. You can check this with any ballistic calculator. A faster bullet will have traveled farther forwards in a given period of time, and thus will reach the apex of its travel farther away. Taken at any distance before then, it will appear to hit lower on the target than a slower bullet.
Posted By: Korean Redneck

Re: POI of heavier vs. lighter bullets - 01/25/21 07:56 PM

Many have chimed in an I tend to agree with barrel harmonics.

Since getting my magnetospeed, I have noticed a general trend that higher velocity bullets shoot higher on paper. However, I've seen a bunch of doozies. Putting a guesstimate, like 60% even with the same bullet shooting the same load do speed vs elevation. That's not enough correlation to be meaningful to me.

Originally Posted by onlysmith&wesson
Originally Posted by HicksHunter
Contrary to popular belief, it has nothing to do with the gun's recoil. The bullet is already long gone by the time the gun is moving backwards. This is even true with slow-moving pistol calibers.

The trajectory of the bullet changes with velocity. You can check this with any ballistic calculator. A faster bullet will have traveled farther forwards in a given period of time, and thus will reach the apex of its travel farther away. Taken at any distance before then, it will appear to hit lower on the target than a slower bullet.

Interesting. I'd like to see a trajectory line for these two, side by side. That would prove it.

What ever it is doing, it does it exactly the same every time with the SST's. I shot it for drop a couple of weeks age at 200, 300 and 400 yards. It worked on a live target the next day at 280 yards. Held the 8" I had from the day before at 300, dead pig.



Attached are graphs from 2 loads I have data for. The ballistic calculation is from the Berger website. You can input the data yourself i you;d like. I know for both loads the 300 yard is pretty spot on and the 600 for the 178 is confirmed from me in terms of the drop.
You can see the lighter 155 with 300fps more velocity reached 1000 yards faster.

Attached picture 308 Time of Flight.png
Attached picture 308 range.png
Posted By: HicksHunter

Re: POI of heavier vs. lighter bullets - 01/25/21 08:07 PM

While harmonics do have a tendency to affect zero in a big way, the general trend of heavier bullets hitting higher at close ranges is not due to this. Ballistic calculators do not account for harmonics- only the mathematics of trajectories. The numbers don't lie.
Posted By: J.G.

Re: POI of heavier vs. lighter bullets - 01/25/21 08:12 PM

Seen plenty of heavier bullets land lower at 100 yards, also.

Ballistic calculators are very helpful thing, and I use them weekly. But they, QuickLoad, published load data, chronographs and a host of other things do not replace rifle range testing and documentation of said testing.

As Captain Ron said "if anything is going to happen, it is going to happen out there."

Long thin barrel, short thick barrel, same twist rate, same exact ammo, I expect different POI on all of them. Even barrels of the same finish length, but with different contours are likely to have varying POIs. All equals harmonics.
Posted By: Adchunts

Re: POI of heavier vs. lighter bullets - 01/25/21 08:12 PM

Have shot three different 130 grain loads from my old .270 Win at the same target, all factory ammo. Two shot almost to the same place at 100 yards. One wasn’t even on the target. I don’t think you could predict where any specific load would print with any sort of accuracy. Gotta shoot it to find out. Although, if you could figure it out, you could theoretically sight in a rifle in the living room without actually shooting it. That would be pretty cool.
Posted By: J.G.

Re: POI of heavier vs. lighter bullets - 01/25/21 08:16 PM

Originally Posted by Adchunts
I don’t think you could predict where any specific load would print with any sort of accuracy. Gotta shoot it to find out. Although, if you could figure it out, you could theoretically sight in a rifle in the living room without actually shooting it. That would be pretty cool.


Preach!
Posted By: Big Fitz

Re: POI of heavier vs. lighter bullets - 01/25/21 08:24 PM

Heavier/slower bullet hitting higher than a lighter/faster bullet at 100 is barrel harmonics provided that everything else is the same.
Posted By: HicksHunter

Re: POI of heavier vs. lighter bullets - 01/25/21 08:27 PM

I hate to say it but you guys are missing the point here. Obviously a load going 1500fps vs 3000fps is going to have a different vertical POI due to a difference in velocity. That is not something that is chalked up to barrel harmonics, and is not what OP was asking about.

Obviously his difference is smaller, but the same trend is there. I can replicate this with my pistols, my rifles, a ballistic calculator, and probably even a crossbow if I had one.
Posted By: onlysmith&wesson

Re: POI of heavier vs. lighter bullets - 01/25/21 08:36 PM

Originally Posted by FiremanJG
Originally Posted by Adchunts
I don’t think you could predict where any specific load would print with any sort of accuracy. Gotta shoot it to find out. Although, if you could figure it out, you could theoretically sight in a rifle in the living room without actually shooting it. That would be pretty cool.


Preach!

Exactly. That is what we were doing. Windage was good, and it did group decently.
Posted By: Texas Dan

Re: POI of heavier vs. lighter bullets - 01/25/21 09:41 PM

Originally Posted by FiremanJG
Bullet probably leaves the barrel at the apex of the sine wave. All is well, as long as it hits consistently.


One of two points at which the barrel is stationary along the harmonic wave.

Just curious if it's possible a given load produces a bullet that leaves the barrel at the bottom of the harmonic wave? If so, you would think this would create a somewhat lower POI.

Posted By: J.G.

Re: POI of heavier vs. lighter bullets - 01/25/21 09:44 PM

Originally Posted by HicksHunter
I hate to say it but you guys are missing the point here. Obviously a load going 1500fps vs 3000fps is going to have a different vertical POI due to a difference in velocity. That is not something that is chalked up to barrel harmonics, and is not what OP was asking about.

Obviously his difference is smaller, but the same trend is there. I can replicate this with my pistols, my rifles, a ballistic calculator, and probably even a crossbow if I had one.


I think you're missing the point, sir.

In factory ammo, as well as hand loads a lighter bullet almost always has a higher muzzle velocity. Therefore it should print higher on paper. I lust finished a ladder test 30 minutes ago because of this. Faster, equals rise on paper. When ammo has a heavier bullet AND is probably slower, but prints higher than a lighter faster bullet, that is due to barrel harmonics. OS&W has found some ammo that is leaving his muzzle at the apex of the sine wave, and good for him. But changing ammo lot numbers can (and probably will) print somewhere else from the 100 yard zero. Same bullet, new powder lot, new velocity, new relationship with the barrel's harmonics.
Posted By: Crews

Re: POI of heavier vs. lighter bullets - 01/25/21 09:45 PM

Originally Posted by HicksHunter
Contrary to popular belief, it has nothing to do with the gun's recoil. The bullet is already long gone by the time the gun is moving backwards. This is even true with slow-moving pistol calibers.


Want to go on record as saying this is absolutely not true. Recoil management (how you drive the gun) ABSOLUTELY influences POI. It may not be happening in this instance, but to claim it's not a possibility is asinine.
Posted By: HicksHunter

Re: POI of heavier vs. lighter bullets - 01/25/21 10:16 PM

Originally Posted by FiremanJG
Originally Posted by HicksHunter
I hate to say it but you guys are missing the point here. Obviously a load going 1500fps vs 3000fps is going to have a different vertical POI due to a difference in velocity. That is not something that is chalked up to barrel harmonics, and is not what OP was asking about.

Obviously his difference is smaller, but the same trend is there. I can replicate this with my pistols, my rifles, a ballistic calculator, and probably even a crossbow if I had one.


I think you're missing the point, sir.

In factory ammo, as well as hand loads a lighter bullet almost always has a higher muzzle velocity. Therefore it should print higher on paper. I lust finished a ladder test 30 minutes ago because of this. Faster, equals rise on paper. When ammo has a heavier bullet AND is probably slower, but prints higher than a lighter faster bullet, that is due to barrel harmonics. OS&W has found some ammo that is leaving his muzzle at the apex of the sine wave, and good for him. But changing ammo lot numbers can (and probably will) print somewhere else from the 100 yard zero. Same bullet, new powder lot, new velocity, new relationship with the barrel's harmonics.


You should plug this into a ballistic calculator and test if this is the case. Change your velocity by 200fps, set your increments to as small as they can get, and check the ballistics tables. It just isn't borne out in reality. Edited to add- This is true within certain distances. A ladder test at longer distances like 200yds may have lighter bullets printing higher if their balance with BC means that they haven't dropped as much.

Like I said, this is a repeatable shift with anything. If it has a sight that is over its bore and it uses a parabolic trajectory, this is predictable and repeatable. A shift due to harmonics instead would not be predictable.

Originally Posted by Crews
Originally Posted by HicksHunter
Contrary to popular belief, it has nothing to do with the gun's recoil. The bullet is already long gone by the time the gun is moving backwards. This is even true with slow-moving pistol calibers.


Want to go on record as saying this is absolutely not true. Recoil management (how you drive the gun) ABSOLUTELY influences POI. It may not be happening in this instance, but to claim it's not a possibility is asinine.





I'd encourage you to watch this part of the video (1:31) at 1/4 speed. Notice how the bolt hasn't even started cycling and the bullet is long gone. This is somewhat related to a previous thread where shooters claimed that the last round in an AR15 shoots differently because the bolt cycles differently, and this video should also debunk that.

I'm not saying that your actions with the rifle don't influence POI. But if you are getting more than an inch of shift at 100yd by changing from sitting to prone, for example, you are dealing with shooter error in the form of parallax or technique. My handguns don't shoot 2" higher at 25 yards with a slower load because my gun is already tilting that much farther upwards.
Posted By: onlysmith&wesson

Re: POI of heavier vs. lighter bullets - 01/25/21 10:19 PM

Originally Posted by FiremanJG
Originally Posted by HicksHunter
I hate to say it but you guys are missing the point here. Obviously a load going 1500fps vs 3000fps is going to have a different vertical POI due to a difference in velocity. That is not something that is chalked up to barrel harmonics, and is not what OP was asking about.

Obviously his difference is smaller, but the same trend is there. I can replicate this with my pistols, my rifles, a ballistic calculator, and probably even a crossbow if I had one.


I think you're missing the point, sir.

In factory ammo, as well as hand loads a lighter bullet almost always has a higher muzzle velocity. Therefore it should print higher on paper. I lust finished a ladder test 30 minutes ago because of this. Faster, equals rise on paper. When ammo has a heavier bullet AND is probably slower, but prints higher than a lighter faster bullet, that is due to barrel harmonics. OS&W has found some ammo that is leaving his muzzle at the apex of the sine wave, and good for him. But changing ammo lot numbers can (and probably will) print somewhere else from the 100 yard zero. Same bullet, new powder lot, new velocity, new relationship with the barrel's harmonics.

All of these reasons given make some sense, and I appreciate all the responses. My reason for asking, if I need to source a new load, what characteristics should I try to duplicate to so stay as close to what I have dope on. Velocity, OAL, wt., etc....Sounds like none of them. Since it did group a different load decent, only higher that tells me I just need to find a good supply of whatever I settle on, like 200 rounds minimum, (This is a hunting rifle, 50 rounds a year is a pile of pigs, a few deer and a handful of coyotes) shoot a new group and move on. I have a 200 + rounds of this Hornady, I'll be good for a while. Never too old to learn. My take away so far is some, if not all of the reasons are at work.
Posted By: J.G.

Re: POI of heavier vs. lighter bullets - 01/26/21 12:39 AM

Originally Posted by HicksHunter
Originally Posted by FiremanJG
Originally Posted by HicksHunter
I hate to say it but you guys are missing the point here. Obviously a load going 1500fps vs 3000fps is going to have a different vertical POI due to a difference in velocity. That is not something that is chalked up to barrel harmonics, and is not what OP was asking about.

Obviously his difference is smaller, but the same trend is there. I can replicate this with my pistols, my rifles, a ballistic calculator, and probably even a crossbow if I had one.


I think you're missing the point, sir.

In factory ammo, as well as hand loads a lighter bullet almost always has a higher muzzle velocity. Therefore it should print higher on paper. I lust finished a ladder test 30 minutes ago because of this. Faster, equals rise on paper. When ammo has a heavier bullet AND is probably slower, but prints higher than a lighter faster bullet, that is due to barrel harmonics. OS&W has found some ammo that is leaving his muzzle at the apex of the sine wave, and good for him. But changing ammo lot numbers can (and probably will) print somewhere else from the 100 yard zero. Same bullet, new powder lot, new velocity, new relationship with the barrel's harmonics.


You should plug this into a ballistic calculator and test if this is the case. Change your velocity by 200fps, set your increments to as small as they can get, and check the ballistics tables. It just isn't borne out in reality. Edited to add- This is true within certain distances. A ladder test at longer distances like 200yds may have lighter bullets printing higher if their balance with BC means that they haven't dropped as much


You're leaning on calculators and the internet too much.

Shoot more rifles, more barrel contours, more bullet weights, more barrel lengths, more muzzle devices, in more weather. Produce volumes of real rifle range data, and I might listen.
Posted By: HicksHunter

Re: POI of heavier vs. lighter bullets - 01/26/21 12:55 AM

Originally Posted by FiremanJG
Originally Posted by HicksHunter
Originally Posted by FiremanJG
Originally Posted by HicksHunter
I hate to say it but you guys are missing the point here. Obviously a load going 1500fps vs 3000fps is going to have a different vertical POI due to a difference in velocity. That is not something that is chalked up to barrel harmonics, and is not what OP was asking about.

Obviously his difference is smaller, but the same trend is there. I can replicate this with my pistols, my rifles, a ballistic calculator, and probably even a crossbow if I had one.


I think you're missing the point, sir.

In factory ammo, as well as hand loads a lighter bullet almost always has a higher muzzle velocity. Therefore it should print higher on paper. I lust finished a ladder test 30 minutes ago because of this. Faster, equals rise on paper. When ammo has a heavier bullet AND is probably slower, but prints higher than a lighter faster bullet, that is due to barrel harmonics. OS&W has found some ammo that is leaving his muzzle at the apex of the sine wave, and good for him. But changing ammo lot numbers can (and probably will) print somewhere else from the 100 yard zero. Same bullet, new powder lot, new velocity, new relationship with the barrel's harmonics.


You should plug this into a ballistic calculator and test if this is the case. Change your velocity by 200fps, set your increments to as small as they can get, and check the ballistics tables. It just isn't borne out in reality. Edited to add- This is true within certain distances. A ladder test at longer distances like 200yds may have lighter bullets printing higher if their balance with BC means that they haven't dropped as much


You're leaning on calculators and the internet too much.

Shoot more rifles, more barrel contours, more bullet weights, more barrel lengths, more muzzle devices, in more weather. Produce volumes of real rifle range data, and I might listen.


I mean this is coming entirely from my own experience, and I'm using the ballistic calculator as way to explain something that happens both in theory and on the range. You aren't the only one with rifle experience, but you are the one who hasn't provided any real data to back up his claim. You do seem to be thinking in terms of a ladder test at long ranges. It's true that all other things held equal, a higher velocity bullet will impact higher at long ranges.

I'm talking specifically about close ranges where the bullet is still on the rise. For example, OP is shooting at 100 yards where most bullets will still be rising. Go ahead and try this the next time you head out to the range. Take your two best shooting loads for two bullet weights, and shoot them at like 50-100 yards. It doesn't even matter what distance you're zeroed for. 100% the slower bullet will shoot higher. Picking two good loads removes your idea of harmonics from the equation, and leaves it solely based on differences in trajectory due to velocity.
Posted By: P_102

Re: POI of heavier vs. lighter bullets - 01/26/21 01:15 AM

“It's true that all other things held equal, a higher velocity bullet will impact higher at long ranges. “

“ It doesn't even matter what distance you're zeroed for. 100% the slower bullet will shoot higher.“

Um, Hick.....which is it?
Posted By: HicksHunter

Re: POI of heavier vs. lighter bullets - 01/26/21 01:17 AM

Originally Posted by P_102
“It's true that all other things held equal, a higher velocity bullet will impact higher at long ranges. “

“ It doesn't even matter what distance you're zeroed for. 100% the slower bullet will shoot higher.“

Um, Hick.....which is it?



Please reread what ranges I'm talking about in my paragraphs.
Posted By: J.G.

Re: POI of heavier vs. lighter bullets - 01/26/21 01:48 AM

I never said or implied I am the only one with experience. You're basing your argument off of theory instead of range time, and actually shooting. If you've got the real world experience, lead with that.

There's a whole lot of people around here that have seen my real data.

Close range, bullets rise to the 100 yard zero. The bullet path intersects at the POA on a well zeroed scope. After 100 yards the bullet is falling, period. Seen it with velocity spreads over 2500 fps different, up to 3400 fps MV. The ballistic calculator has no place inside of 100 yards for a center fire rifle round. Case in point, "The MOA Walk Back." Start at 7 yards, and hit a 1 MOA dot. Back up to 17 yards, 27, 37, 47, all the way to 77 yards. Plug in a scope height to the .01", plug in bullet weight, BC, MV and ask the calculator what the corrections are. Ask more than one calculator and you'll get a difference every time. And none of them are correct. Why? It is all theoretical. Only way to get close in DOPE is like any other DOPE, Data On Previous Engagement, ya gotta shoot it for real. Lost 8 out of 10 points the first time I encountered it. The next month, I cleaned it, because I had shot it at my home range.

Shooting at 50 and 100 yards for two different MVs is going to yeild the exact results I expect. I expect it because I have already done it. .223, .223 A.I., .22-250, .243, 6.5 Creedmoor, 7mm-08, 7mm-08 A I. .308, 7 Rem Mag. Every one of them a different MV, every one of them a different bullet (Except the 7mm-08s), every one of them a different MV. Zeroed at 100 yards, .4 or .5 Mil at 50 yards. .3, .4, or .5 Mil at 200 yards.
Posted By: GasGuzzler

Re: POI of heavier vs. lighter bullets - 01/26/21 01:59 AM

You realize there is an ammo and reloading sub-forum a couple spots down from this firearm discussion sub-forum, correct?
Posted By: HicksHunter

Re: POI of heavier vs. lighter bullets - 01/26/21 02:20 AM

Originally Posted by FiremanJG
I never said or implied I am the only one with experience. You're basing your argument off of theory instead of range time, and actually shooting. If you've got the real world experience, lead with that.

There's a whole lot of people around here that have seen my real data.

Close range, bullets rise to the 100 yard zero. The bullet path intersects at the POA on a well zeroed scope. After 100 yards the bullet is falling, period. Seen it with velocity spreads over 2500 fps different, up to 3400 fps MV. The ballistic calculator has no place inside of 100 yards for a center fire rifle round. Case in point, "The MOA Walk Back." Start at 7 yards, and hit a 1 MOA dot. Back up to 17 yards, 27, 37, 47, all the way to 77 yards. Plug in a scope height to the .01", plug in bullet weight, BC, MV and ask the calculator what the corrections are. Ask more than one calculator and you'll get a difference every time. And none of them are correct. Why? It is all theoretical. Only way to get close in DOPE is like any other DOPE, Data On Previous Engagement, ya gotta shoot it for real. Lost 8 out of 10 points the first time I encountered it. The next month, I cleaned it, because I had shot it at my home range.

Shooting at 50 and 100 yards for two different MVs is going to yeild the exact results I expect. I expect it because I have already done it. .223, .223 A.I., .22-250, .243, 6.5 Creedmoor, 7mm-08, 7mm-08 A I. .308, 7 Rem Mag. Every one of them a different MV, every one of them a different bullet (Except the 7mm-08s), every one of them a different MV. Zeroed at 100 yards, .4 or .5 Mil at 50 yards. .3, .4, or .5 Mil at 200 yards.


Try the experiment I suggested and report back. I'll buy you a beer next time you drive through New Braunfels if I'm wrong.
Posted By: cowie14

Re: POI of heavier vs. lighter bullets - 01/26/21 02:45 AM

Originally Posted by HicksHunter


It's true that all other things held equal, a higher velocity bullet will impact higher at long ranges.




This is not true at all
Posted By: patriot07

Re: POI of heavier vs. lighter bullets - 01/26/21 02:48 AM

I've done ladder tests at 300 yards where the faster loads (same weight) shoot lower than the slower loads. The answer is harmonics. Any time you change anything (bullet weight, pressure, speed, charge, adding/removing muzzle brake or suppressor, sometimes just changing the stock or action screw torque, etc.), the barrel will act differently. The goal of handloading is to find the spot in the harmonics that is most forgiving and allows for the smallest variance in output.
Posted By: cowie14

Re: POI of heavier vs. lighter bullets - 01/26/21 02:58 AM

Positive compensation, that is the word you are looking for. Alex Wheeler knows more about it than anyone especially at 1k

http://www.geoffrey-kolbe.com/articles/rimfire_accuracy/tuning_a_barrel.htm

Here is an example at 600 yds:

42.4 2776fps
42.5 2786
42.8 2786
42.9 2805

not sure the group but maybe 1.25"

[Linked Image]


Posted By: P_102

Re: POI of heavier vs. lighter bullets - 01/26/21 03:23 AM

Originally Posted by HicksHunter
Originally Posted by P_102
“It's true that all other things held equal, a higher velocity bullet will impact higher at long ranges. “

“ It doesn't even matter what distance you're zeroed for. 100% the slower bullet will shoot higher.“

Um, Hick.....which is it?



Please reread what ranges I'm talking about in my paragraphs.


Both of those statements discount ranges altogether, especially when you start throwing around 100%.
Posted By: unclebubba

Re: POI of heavier vs. lighter bullets - 01/26/21 03:26 AM

Hickshunter, you are plugging those numbers into an online calculator. That online calculator is asking about your zero distance, right? As you are changing velocity, but not changing your zero distance, the calculator is angling the barrel up to compensate for the difference in drop. That's why your numbers are wrong. Try the calculator with a zero distance of zero. Then you will see that the heavier bullet will drop faster and print lower based on physics. The only thing that calculator can't account for is harmonics.
Posted By: patriot07

Re: POI of heavier vs. lighter bullets - 01/26/21 03:31 AM

Ballistic calculator has zero to do with the question asked.

The question asked was "I shot a bunch of bullets and set zero. Then I shot some other bullets (different weight/charge/velocity/etc) and they shot higher even though they were heavier. Why?"

The answer is two words: barrel harmonics
Posted By: Big Fitz

Re: POI of heavier vs. lighter bullets - 01/26/21 03:42 AM

Originally Posted by Big Fitz
Heavier/slower bullet hitting higher than a lighter/faster bullet at 100 is barrel harmonics provided that everything else is the same.


^^^ this dude is brilliant!
Posted By: wp75169

Re: POI of heavier vs. lighter bullets - 01/26/21 03:42 AM

roflmao
Posted By: Big Fitz

Re: POI of heavier vs. lighter bullets - 01/26/21 03:49 AM

Originally Posted by wp75169
roflmao


cheers
Posted By: patriot07

Re: POI of heavier vs. lighter bullets - 01/26/21 03:58 AM

Originally Posted by Big Fitz
Originally Posted by wp75169
roflmao


cheers

happy3
Posted By: JCO

Re: POI of heavier vs. lighter bullets - 01/26/21 04:39 AM

nidea

Over my head. When I try to think that hard it gives me a migraine.
Posted By: 10 Gauge

Re: POI of heavier vs. lighter bullets - 01/26/21 06:28 AM

I think it has more to do with harmonics than anything, comparing the POI of different loads at 100 yards. You can probably pick ten loads and shoot ten groups at a different point of impact with each load without adjusting the scope. Even with the exact same factory load, different lot of ammo, there is a good chance the new lot will have a different poi maybe by a lot or maybe by a little.

I have had two boxes of 170 grain corelokt 30-30 shoot two completely different poi by nearly 6” at 100 yards. I have experience the same thing with two different boxes of 80 grain Winchester PowerPoint .243 ammo.

Difference in POI with different loads has little if anything to do with velocity, weight, or BC inside 100 yards.
Posted By: HicksHunter

Re: POI of heavier vs. lighter bullets - 01/26/21 11:05 AM

Originally Posted by patriot07
Ballistic calculator has zero to do with the question asked.

The question asked was "I shot a bunch of bullets and set zero. Then I shot some other bullets (different weight/charge/velocity/etc) and they shot higher even though they were heavier. Why?"

The answer is two words: barrel harmonics


I mean it's literally a question of trajectories, but okay.

Originally Posted by unclebubba
Hickshunter, you are plugging those numbers into an online calculator. That online calculator is asking about your zero distance, right? As you are changing velocity, but not changing your zero distance, the calculator is angling the barrel up to compensate for the difference in drop. That's why your numbers are wrong. Try the calculator with a zero distance of zero. Then you will see that the heavier bullet will drop faster and print lower based on physics. The only thing that calculator can't account for is harmonics.


Okay, this is actually a fair point. Unfortunately a zero distance of 0 yards wouldn't make any sense. The angles of the scope and the gun would have to be similar to a pizza slice. The trajectory at 25 yards has it rising 112 inches, lol.

The fact that the ballistic calculator is having to account for a slow bullet hitting higher at close ranges is really proof that velocity is causing OP's changes.


Originally Posted by cowie14
Positive compensation, that is the word you are looking for. Alex Wheeler knows more about it than anyone especially at 1k

http://www.geoffrey-kolbe.com/articles/rimfire_accuracy/tuning_a_barrel.htm

Here is an example at 600 yds:

42.4 2776fps
42.5 2786
42.8 2786
42.9 2805

not sure the group but maybe 1.25"

[im]https://texashuntingforum.com/forum/pics/userpics/2021/01/full-66266-277481-img_4970.jpg[/img]




This is really interesting, thanks for sharing. It does help explain why ladder testing is such a useful tool and how a rimfire barrel might be tuned for harmonics. Unfortunately, it just can't explain a 2" shift at 100 yards with accurate loads. A good shooting load that is tuned to your barrel's harmonics (minimal vertical dispersion) accounts for this, and thus any changes in POI are due to the trajectory of the bullets.
Posted By: onlysmith&wesson

Re: POI of heavier vs. lighter bullets - 01/26/21 12:38 PM

This is great information. I haven't spent a lot of time thinking it through at this level because I've never had to. I got lucky and found great ammo that has worked and bought it for years. I always got my own DOPE on paper at ranges out to 400. I haven't noticed lot to lot POI changes. Now that I may be looking for something different, I'm learning some new stuff.

We all know there's one hell of an explosion in the chamber and a huge pressure spike right there. It causes barrel movement. Call it harmonics (vibrations=movement) or very mild recoil. If this is to have an effect on POI, it has to occur before the bullet leaves the bore. It occurred on the first shot. I think if in my original post if I had stated "upward movement" instead of "recoil" there would be more agreement here. I'll drop the time in the barrel part of that theory. A different load and different weight of bullet would definitely create a different amount of pressure in the chamber, creating different movement-vibration-harmonics-mild recoil and effect POI.

I think the trajectory also comes into play, all things equal.

Now for the platform. Could all of this be exponential given that this is an AR (a good one) and my scope is way higher than most of our thinking on a typical discussion on this? Would there be more harmonic effect due to the way the barrel is supported in the action over a bolt rifle, and my scope height of about 2.550" have a greater effect on the trajectory over an average height of say 1.500".
Posted By: J.G.

Re: POI of heavier vs. lighter bullets - 01/26/21 01:04 PM

Scope height, and barrel connected to action have nothing to do with this.

You build a leather whip 10' long and I build a leather whip 9' long. They will have different sine waves. That is rifle barrels.
Posted By: onlysmith&wesson

Re: POI of heavier vs. lighter bullets - 01/26/21 01:10 PM

Originally Posted by FiremanJG
Scope height, and barrel connected to action have nothing to do with this.

You build a leather whip 10' long and I build a leather whip 9' long. They will have different sine waves. That is rifle barrels.

And this is not compounded by the action, it would be the same in a bolt action, all things equal?
Posted By: wp75169

Re: POI of heavier vs. lighter bullets - 01/26/21 01:15 PM

For the sake of understanding let’s quit using the words “harmonics” and “sine wave”. Both are correct but for the sake of understanding let’s call it “barrel whip”. As in the movement a whip makes when you snap it.

Everyone may already be on the same page but I don’t think so.

Which way is the tail of the whip (barrel) pointed when the bullet exits, up or down?
Posted By: wp75169

Re: POI of heavier vs. lighter bullets - 01/26/21 01:17 PM

Originally Posted by FiremanJG
Scope height, and barrel connected to action have nothing to do with this.

You build a leather whip 10' long and I build a leather whip 9' long. They will have different sine waves. That is rifle barrels.



Guess I should have read before I posted. You pretty much cover it here.
Posted By: HicksHunter

Re: POI of heavier vs. lighter bullets - 01/26/21 01:32 PM

Originally Posted by wp75169
For the sake of understanding let’s quit using the words “harmonics” and “sine wave”. Both are correct but for the sake of understanding let’s call it “barrel whip”. As in the movement a whip makes when you snap it.

Everyone may already be on the same page but I don’t think so.

Which way is the tail of the whip (barrel) pointed when the bullet exits, up or down?


This makes about as much difference at close ranges as compensating for spin drift.
Posted By: J.G.

Re: POI of heavier vs. lighter bullets - 01/26/21 01:39 PM

Originally Posted by HicksHunter
Originally Posted by wp75169
For the sake of understanding let’s quit using the words “harmonics” and “sine wave”. Both are correct but for the sake of understanding let’s call it “barrel whip”. As in the movement a whip makes when you snap it.

Everyone may already be on the same page but I don’t think so.

Which way is the tail of the whip (barrel) pointed when the bullet exits, up or down?


This makes about as much difference at close ranges as compensating for spin drift.


You can continue to argue with, well everyone else in this thread. And you will still be wrong.
Posted By: wp75169

Re: POI of heavier vs. lighter bullets - 01/26/21 01:48 PM

Originally Posted by HicksHunter
Originally Posted by wp75169
For the sake of understanding let’s quit using the words “harmonics” and “sine wave”. Both are correct but for the sake of understanding let’s call it “barrel whip”. As in the movement a whip makes when you snap it.

Everyone may already be on the same page but I don’t think so.

Which way is the tail of the whip (barrel) pointed when the bullet exits, up or down?


This makes about as much difference at close ranges as compensating for spin drift.



Then explain why we do load development instead of just loading everything to max? It’s not uncommon to have big groups in between two good ones. It’s suggested you will find two good nodes, one low and one high. They’re referring to powder charge and velocity, but often the faster load will print lower on the 100 yard target. Hmmm.... wonder if those two nodes are the top and bottom of the arc on the sine wave where the barrel is static for a moment before changing directions? I think JG covered that on the last page though.

I guess we have to agree to disagree.
Posted By: HicksHunter

Re: POI of heavier vs. lighter bullets - 01/26/21 01:56 PM

Originally Posted by wp75169
Originally Posted by HicksHunter
Originally Posted by wp75169
For the sake of understanding let’s quit using the words “harmonics” and “sine wave”. Both are correct but for the sake of understanding let’s call it “barrel whip”. As in the movement a whip makes when you snap it.

Everyone may already be on the same page but I don’t think so.

Which way is the tail of the whip (barrel) pointed when the bullet exits, up or down?


This makes about as much difference at close ranges as compensating for spin drift.



Then explain why we do load development instead of just loading everything to max? It’s not uncommon to have big groups in between two good ones. It’s suggested you will find two good nodes, one low and one high. They’re referring to powder charge and velocity, but often the faster load will print lower on the 100 yard target. Hmmm.... wonder if those two nodes are the top and bottom of the arc on the sine wave where the barrel is static for a moment before changing directions? I think JG covered that on the last page though.

I guess we have to agree to disagree.


Help me understand this. You guys are saying that if you are testing a series of powder charges from low to high at 100 yards, instead of seeing a general trend of the bullets hitting lower and lower until you hit max charge, you will see oscillations up and down in POI of 2" and more? You aren't simply describing finding an accuracy node, you are implying that the barrel is whipping so severely and shifting your POI that no trend can be deduced!
Posted By: cxjcherokec

Re: POI of heavier vs. lighter bullets - 01/26/21 03:25 PM

Here is a real world experience Hicks, proving its harmonics. My sons 6.5CM prints a 0 with 140gr AMAX. Put on the AAC can and note there is a POI shift 1" lower than w/o. MV stayed the same, same lot, same bullet, everything is 100% the same minus adding the can. THAT proves harmonics, without a doubt.
Posted By: kmon11

Re: POI of heavier vs. lighter bullets - 01/26/21 03:27 PM

Barrels move, vibrate/whip/what ever. Short stiff barrels do less than long thin barrels but all experience it to an extent. We that are reloaders looking for precision find out "node" for accuracy which generally will be when the barrel is moving less at the time the bullet exits the barrel. Different things have been used over the years to try and minimize the amount of movement. Many production manufactures leave a wood bump in their wood stocks near the end of the forearm to provide a dampening of the resonance of the barrel when firing to reduce the harmonic shifts when shooting. Remington and Sako are a couple that certainly have. Barrel tuners used in 22s are also employed by come in centerfire, think Browning BOSS.

There are some interesting videos showing barrel whip using high speed cameras to catch it. Muzzle breaks and other devices enhance it but the bullet has left th barrel before the whip caused by them happens yet there is movement while the bullet is in the barrel.





Posted By: HicksHunter

Re: POI of heavier vs. lighter bullets - 01/26/21 03:46 PM

Originally Posted by cxjcherokec
Here is a real world experience Hicks, proving its harmonics. My sons 6.5CM prints a 0 with 140gr AMAX. Put on the AAC can and note there is a POI shift 1" lower than w/o. MV stayed the same, same lot, same bullet, everything is 100% the same minus adding the can. THAT proves harmonics, without a doubt.


And then as he changes his load, what happens to his POI?

I'm sorry, but hanging a weight off the end of a barrel is not conclusive proof that ammunition changes harmonics enough to shift POI 2" or more at 100yd. The question is "why do heavier bullets hit higher at this distance," and the only real answer is "trajectory differences."
Posted By: J.G.

Re: POI of heavier vs. lighter bullets - 01/26/21 03:59 PM

Originally Posted by HicksHunter
Originally Posted by cxjcherokec
Here is a real world experience Hicks, proving its harmonics. My sons 6.5CM prints a 0 with 140gr AMAX. Put on the AAC can and note there is a POI shift 1" lower than w/o. MV stayed the same, same lot, same bullet, everything is 100% the same minus adding the can. THAT proves harmonics, without a doubt.


And then as he changes his load, what happens to his POI?

I'm sorry, but hanging a weight off the end of a barrel is not conclusive proof that ammunition changes harmonics enough to shift POI 2" or more at 100yd. The question is "why do heavier bullets hit higher at this distance," and the only real answer is "trajectory differences."


Only trajectory difference is the heavier bullet left the muzzle when the muzzle was flexed upward. The lighter bullet, the muzzle was not at apex of the sine wave. Heavier bullet left higher, so it hits higher.

Barrel harmonics.

I've shot countless 500 yard ladder tests .224" bullets, everything in between up to .338" bullets, short action to big magnums. Same components, only difference is powder charge. Many times, with high end custom rifles, I've seen sub 1/4 MOA groups with three different charges in the group. I've also seen hotter charges land lower than lighter charges. Why? The lighter charges were not in the accuracy node. And the accuracy node is a muzzle at apex of sine wave.

Barrel harmonics.
Posted By: HicksHunter

Re: POI of heavier vs. lighter bullets - 01/26/21 04:06 PM

Originally Posted by FiremanJG
Originally Posted by HicksHunter
Originally Posted by cxjcherokec
Here is a real world experience Hicks, proving its harmonics. My sons 6.5CM prints a 0 with 140gr AMAX. Put on the AAC can and note there is a POI shift 1" lower than w/o. MV stayed the same, same lot, same bullet, everything is 100% the same minus adding the can. THAT proves harmonics, without a doubt.


And then as he changes his load, what happens to his POI?

I'm sorry, but hanging a weight off the end of a barrel is not conclusive proof that ammunition changes harmonics enough to shift POI 2" or more at 100yd. The question is "why do heavier bullets hit higher at this distance," and the only real answer is "trajectory differences."


Only trajectory difference is the heavier bullet left the muzzle when the muzzle was flexed upward. The lighter bullet, the muzzle was not at apex of the sine wave. Heavier bullet left higher, so it hits higher.

Barrel harmonics.

I've shot countless 500 yard ladder tests .224" bullets, everything in between up to .338" bullets, short action to big magnums. Same components, only difference is powder charge. Many times, with high end custom rifles, I've seen sub 1/4 MOA groups with three different charges in the group. I've also seen hotter charges land lower than lighter charges. Why? The lighter charges were not in the accuracy node. And the accuracy node is a muzzle at apex of sine wave.

Barrel harmonics.


As I posted earlier, I'd be interested to hear your guess as to what would happen here:

"Help me understand this. You guys are saying that if you are testing a series of powder charges from low to high at 100 yards, instead of seeing a general trend of the bullets hitting lower and lower until you hit max charge, you will see oscillations up and down in POI of 2" and more? You aren't simply describing finding an accuracy node, you are implying that the barrel is whipping so severely and shifting your POI that no trend can be deduced!"

Again, please keep in mind that we're talkng about short distances where the bullet is still on the rise, not a 500yd ladder test.
Posted By: redchevy

Re: POI of heavier vs. lighter bullets - 01/26/21 04:09 PM

Originally Posted by HicksHunter

As I posted earlier, I'd be interested to hear your guess as to what would happen here:

"Help me understand this. You guys are saying that if you are testing a series of powder charges from low to high at 100 yards, instead of seeing a general trend of the bullets hitting lower and lower until you hit max charge, you will see oscillations up and down in POI of 2" and more? You aren't simply describing finding an accuracy node, you are implying that the barrel is whipping so severely and shifting your POI that no trend can be deduced!"

Again, please keep in mind that we're talkng about short distances where the bullet is still on the rise, not a 500yd ladder test.

So do you believe that all horizontal dispersion in grouping is caused by shooter inconsistency alone?
Posted By: cxjcherokec

Re: POI of heavier vs. lighter bullets - 01/26/21 04:15 PM

Originally Posted by HicksHunter
Originally Posted by cxjcherokec
Here is a real world experience Hicks, proving its harmonics. My sons 6.5CM prints a 0 with 140gr AMAX. Put on the AAC can and note there is a POI shift 1" lower than w/o. MV stayed the same, same lot, same bullet, everything is 100% the same minus adding the can. THAT proves harmonics, without a doubt.


And then as he changes his load, what happens to his POI?

I'm sorry, but hanging a weight off the end of a barrel is not conclusive proof that ammunition changes harmonics enough to shift POI 2" or more at 100yd. The question is "why do heavier bullets hit higher at this distance," and the only real answer is "trajectory differences."


My point was that barrel harmonics play a factor in POI shift. You claim its all based on MV and BC and harmonics play no role. I proved that wrong
Posted By: wp75169

Re: POI of heavier vs. lighter bullets - 01/26/21 04:17 PM

Mine is not “on the rise” @ 100 yards. Some may be.

[Linked Image]
Posted By: HicksHunter

Re: POI of heavier vs. lighter bullets - 01/26/21 04:19 PM

I guess I'll have to bow out of the thread here. If you guys want to perpetuate fuddlore, go for it.
Posted By: redchevy

Re: POI of heavier vs. lighter bullets - 01/26/21 04:25 PM

Originally Posted by HicksHunter
I guess I'll have to bow out of the thread here. If you guys want to perpetuate fuddlore, go for it.

A lot is learned through disagreements. Keep it civil and its all ok.

Dont ask one side to see it your way if your not willing to look at it from the other side as well.
Posted By: TLew

Re: POI of heavier vs. lighter bullets - 01/26/21 04:57 PM

Originally Posted by redchevy
Dont ask one side to see it your way if your not willing to look at it from the other side as well.


Repeat for bunker? grin
Posted By: J.G.

Re: POI of heavier vs. lighter bullets - 01/26/21 05:01 PM

Originally Posted by HicksHunter
Originally Posted by FiremanJG
Originally Posted by HicksHunter
Originally Posted by cxjcherokec
Here is a real world experience Hicks, proving its harmonics. My sons 6.5CM prints a 0 with 140gr AMAX. Put on the AAC can and note there is a POI shift 1" lower than w/o. MV stayed the same, same lot, same bullet, everything is 100% the same minus adding the can. THAT proves harmonics, without a doubt.


And then as he changes his load, what happens to his POI?

I'm sorry, but hanging a weight off the end of a barrel is not conclusive proof that ammunition changes harmonics enough to shift POI 2" or more at 100yd. The question is "why do heavier bullets hit higher at this distance," and the only real answer is "trajectory differences."


Only trajectory difference is the heavier bullet left the muzzle when the muzzle was flexed upward. The lighter bullet, the muzzle was not at apex of the sine wave. Heavier bullet left higher, so it hits higher.

Barrel harmonics.

I've shot countless 500 yard ladder tests .224" bullets, everything in between up to .338" bullets, short action to big magnums. Same components, only difference is powder charge. Many times, with high end custom rifles, I've seen sub 1/4 MOA groups with three different charges in the group. I've also seen hotter charges land lower than lighter charges. Why? The lighter charges were not in the accuracy node. And the accuracy node is a muzzle at apex of sine wave.

Barrel harmonics.


As I posted earlier, I'd be interested to hear your guess as to what would happen here:

"Help me understand this. You guys are saying that if you are testing a series of powder charges from low to high at 100 yards, instead of seeing a general trend of the bullets hitting lower and lower until you hit max charge, you will see oscillations up and down in POI of 2" and more? You aren't simply describing finding an accuracy node, you are implying that the barrel is whipping so severely and shifting your POI that no trend can be deduced!"

Again, please keep in mind that we're talkng about short distances where the bullet is still on the rise, not a 500yd ladder test.


You can see POI shift of 2" and more at 100 yards, absolutely. I don't load test at 100 yards. But I will foul and check zero at 100 yards. And yes, sometimes you cannot see a trend on a BAD powder charge. It is what is called erratic. My charges are within .02 gr from one case to the next, so the ammo shot to shot is extremely consistent. But extremely consistent on an improper powder charge will still shoot poorly. Find the right charge and the load tightens up.
Posted By: J.G.

Re: POI of heavier vs. lighter bullets - 01/26/21 05:02 PM

Originally Posted by HicksHunter
I guess I'll have to bow out of the thread here. If you guys want to perpetuate fuddlore, go for it.


Fuddlore?

Add all of us together and it is over 100,000 rounds of experience.
Posted By: Smokey Bear

Re: POI of heavier vs. lighter bullets - 01/26/21 05:26 PM

Hicks, I’ve been following along here and you are off the mark. I respect the fact you have given a lot of thought to cause and effect however your logic is flawed. A 100 yard zero is load specific in a given rifle. Only after we have various Bullets leaving the muzzle in the same exact same direction can we compare trajectories. When the cartridge goes off, the barreled action writhes like a snake in all directions, not just up and down. Precise bedding, heavy barrels and pressure points are among the things used to dampen the shock wave that bounces up and down the barreled action until it dissipates after the cartridge is fired. We go to great lengths to shore up the bedding in order to find a powder charge where the shock wave has bounced back into the action and the muzzle is at its most stable when the bullet leaves the bore. The reality is until we shoot the various loads in a given rifle, the point of impact is a mystery due to barrel harmonics. Once we find a load that leaves the muzzle where it is in a stable position it is utterly repeatable.
Posted By: Crews

Re: POI of heavier vs. lighter bullets - 01/26/21 07:25 PM

Originally Posted by Smokey Bear
Hicks, I’ve been following along here and you are off the mark.


Worth repeating.
Posted By: patriot07

Re: POI of heavier vs. lighter bullets - 01/26/21 08:24 PM

Originally Posted by Crews
Originally Posted by Smokey Bear
Hicks, I’ve been following along here and you are off the mark.


Worth repeating.

+2
Posted By: Texas Dan

Re: POI of heavier vs. lighter bullets - 01/26/21 08:26 PM

Yes, there is a bit of a "swamp" in this as well as the Ammo Forum.
Posted By: HicksHunter

Re: POI of heavier vs. lighter bullets - 01/26/21 09:06 PM

Again, I challenge anyone here to shoot their two best shooting loads of different grains and/or velocity at a distance closer than their zero (thanks for helping clarify this, WP), and post a picture of your results. 100% the slower bullet will impact higher, negating the idea that it's due to harmonics.

I'll even film a video next time I go to the range demonstrating this with several firearms. Handguns and rifles of both centerfire and rimfire varieties.
Posted By: J.G.

Re: POI of heavier vs. lighter bullets - 01/26/21 09:13 PM

bang
Posted By: HicksHunter

Re: POI of heavier vs. lighter bullets - 01/26/21 09:16 PM

I can relate.

For pete's sake, why is it such a common thing to suggest changing bullet weights in a pistol when it doesn't shoot to POI with fixed sights? It's definitely not barrel whip because 100% of the time it's suggested to go with a heavier, slower bullet.
Posted By: P_102

Re: POI of heavier vs. lighter bullets - 01/26/21 09:29 PM

Originally Posted by HicksHunter
Again, I challenge anyone here to shoot their two best shooting loads of different grains and/or velocity at a distance closer than their zero (thanks for helping clarify this, WP), and post a picture of your results. 100% the slower bullet will impact higher, negating the idea that it's due to harmonics.

I'll even film a video next time I go to the range demonstrating this with several firearms. Handguns and rifles of both centerfire and rimfire varieties.


The two BEST SHOOTING loads are likely leaving the barrel at the top of the ‘wave’ which may make your statement correct...unfortunately that has ZERO to do with the question Mr. Fudd.
Posted By: HicksHunter

Re: POI of heavier vs. lighter bullets - 01/26/21 09:31 PM

Originally Posted by P_102
Originally Posted by HicksHunter
Again, I challenge anyone here to shoot their two best shooting loads of different grains and/or velocity at a distance closer than their zero (thanks for helping clarify this, WP), and post a picture of your results. 100% the slower bullet will impact higher, negating the idea that it's due to harmonics.

I'll even film a video next time I go to the range demonstrating this with several firearms. Handguns and rifles of both centerfire and rimfire varieties.


The two BEST SHOOTING loads are likely leaving the barrel at the top of the ‘wave’ which may make your statement correct...unfortunately that has ZERO to do with the question Mr. Fudd.


Ahh, so you're saying that the two best shooting loads would have an identical POI? Even with different velocities?

Because this is demonstrably false.
Posted By: P_102

Re: POI of heavier vs. lighter bullets - 01/26/21 09:33 PM

Please point out where I said that.......or do you have a difficult time with English?
Posted By: patriot07

Re: POI of heavier vs. lighter bullets - 01/26/21 09:33 PM

Originally Posted by HicksHunter
Again, I challenge anyone here to shoot their two best shooting loads of different grains and/or velocity at a distance closer than their zero (thanks for helping clarify this, WP), and post a picture of your results. 100% the slower bullet will impact higher, negating the idea that it's due to harmonics.

I'll even film a video next time I go to the range demonstrating this with several firearms. Handguns and rifles of both centerfire and rimfire varieties.


I'm not burning a $20 range fee and $20 in ammo to prove what we already know to someone who refuses to consider the fact that they might be wrong.
Posted By: J.G.

Re: POI of heavier vs. lighter bullets - 01/26/21 09:34 PM

Originally Posted by HicksHunter
Again, I challenge anyone here to shoot their two best shooting loads of different grains and/or velocity at a distance closer than their zero (thanks for helping clarify this, WP), and post a picture of your results. 100% the slower bullet will impact higher, negating the idea that it's due to harmonics.

I'll even film a video next time I go to the range demonstrating this with several firearms. Handguns and rifles of both centerfire and rimfire varieties.


You're suggesting a bullet is on the fall at 100 yards then.

That is 100% false. Center fire rifles rise from muzzle to 100 yards, and fall after 100 yards.
Posted By: HicksHunter

Re: POI of heavier vs. lighter bullets - 01/26/21 09:40 PM

Originally Posted by P_102
Please point out where I said that.......or do you have a difficult time with English?


Ahh, was reading on my phone, misunderstood.

The leaving at the top of the wave is exactly the point, though. It controls for this wacky idea of wildly shifting POI due to harmonics. Two loads that seem to agree with the harmonics of the barrel should have the same POI according to JG, right?
Posted By: HicksHunter

Re: POI of heavier vs. lighter bullets - 01/26/21 09:40 PM

Originally Posted by FiremanJG
Originally Posted by HicksHunter
Again, I challenge anyone here to shoot their two best shooting loads of different grains and/or velocity at a distance closer than their zero (thanks for helping clarify this, WP), and post a picture of your results. 100% the slower bullet will impact higher, negating the idea that it's due to harmonics.

I'll even film a video next time I go to the range demonstrating this with several firearms. Handguns and rifles of both centerfire and rimfire varieties.


You're suggesting a bullet is on the fall at 100 yards then.

That is 100% false. Center fire rifles rise from muzzle to 100 yards, and fall after 100 yards.


How do you figure? This entire thread I've been talking about short ranges where the bullet is still rising.

And you realize you can have a sharper trajectory than just having a 100yd zero be the apex of travel right? My M16A4, for example, has a 36/300 zero, and shoots several inches high at 100 yards.
Posted By: J.G.

Re: POI of heavier vs. lighter bullets - 01/26/21 09:47 PM

Because you said the slower bullet will be higher than the faster bullet. That would be you suggesting the bullet was on the fall inside 100 yards. It is not.

Go back and re-read me telling you about the "MOA Walk back".

That rifle I learned it on, 7 yard correction was the same as 875 yard correction. Almost everything out there, to hit perfect at 50 yards, is exactly the same correction to hit perfect at 200 yards. Sight height has a whole lot to do with it. In fact that is most of it.
Posted By: HicksHunter

Re: POI of heavier vs. lighter bullets - 01/26/21 09:48 PM

Originally Posted by FiremanJG
Because you said the slower bullet will be higher than the faster bullet. That would be you suggesting the bullet was on the fall inside 100 yards. It is not.

Go back and re-read me telling you about the "MOA Walk back".

That rifle I learned it on, 7 yard correction was the same as 875 yard correction. Almost everything out there, to hit perfect at 50 yards, is exactly the same correction to hit perfect at 200 yards. Sight height has a whole lot to do with it. In fact that is most of it.


Yes, that's exactly what I said. When the bullets are still rising, the slower bullet will be higher than the faster bullet.
Posted By: J.G.

Re: POI of heavier vs. lighter bullets - 01/26/21 09:51 PM

Originally Posted by HicksHunter
Originally Posted by FiremanJG
Because you said the slower bullet will be higher than the faster bullet. That would be you suggesting the bullet was on the fall inside 100 yards. It is not.

Go back and re-read me telling you about the "MOA Walk back".

That rifle I learned it on, 7 yard correction was the same as 875 yard correction. Almost everything out there, to hit perfect at 50 yards, is exactly the same correction to hit perfect at 200 yards. Sight height has a whole lot to do with it. In fact that is most of it.


Yes, that's exactly what I said. When the bullets are still rising, the slower bullet will be higher than the faster bullet.


At 20, 40, 60 yards?

No it won't. 2000 fps MV on the slow one, 3000 fps MV, no the slow one won't be higher. Because both of them are rising to 100 yards.
Posted By: P_102

Re: POI of heavier vs. lighter bullets - 01/26/21 09:53 PM

Originally Posted by HicksHunter
Originally Posted by P_102
Please point out where I said that.......or do you have a difficult time with English?


Ahh, was reading on my phone, misunderstood.

The leaving at the top of the wave is exactly the point, though. It controls for this wacky idea of wildly shifting POI due to harmonics. Two loads that seem to agree with the harmonics of the barrel should have the same POI according to JG, right?


Incorrect, JG nor anyone else here has said that. Everyone here has argued that, due to harmonics, the bullets could be leaving the barrel when it is at different points in the wave (top, bottom, middle or even right/left) which causes the discrepancy.....

You seem to be having a problem understanding that ballistics and harmonics are two completely different things.
Posted By: HicksHunter

Re: POI of heavier vs. lighter bullets - 01/26/21 09:55 PM

Originally Posted by FiremanJG
Originally Posted by HicksHunter
Originally Posted by FiremanJG
Because you said the slower bullet will be higher than the faster bullet. That would be you suggesting the bullet was on the fall inside 100 yards. It is not.

Go back and re-read me telling you about the "MOA Walk back".

That rifle I learned it on, 7 yard correction was the same as 875 yard correction. Almost everything out there, to hit perfect at 50 yards, is exactly the same correction to hit perfect at 200 yards. Sight height has a whole lot to do with it. In fact that is most of it.


Yes, that's exactly what I said. When the bullets are still rising, the slower bullet will be higher than the faster bullet.


At 20, 40, 60 yards?

No it won't. 2000 fps MV on the slow one, 3000 fps MV, no the slow one won't be higher. Because both of them are rising to 100 yards.


Now you're starting to understand the parameters. 20, 40, and 60 yards are all excellent testing points. Go give it a shot with your two best shooting loads, 100% the slower load will print higher.
Posted By: redchevy

Re: POI of heavier vs. lighter bullets - 01/26/21 10:07 PM

If the rifle is zeroed with both bullets i think I can see HicksHunter's side.

I have fired slower/heavier rounds out of a rifle that impacted higher at 100 yards than lighter faster bullets in the same rifle when the rifle was not individually zeroed.

My factory rem 180 grain 30-06 is zeroed at 100 yards. It is on the fall at 100 yards. It has a zero at appx 50 and 100 yards.
Posted By: cxjcherokec

Re: POI of heavier vs. lighter bullets - 01/26/21 11:21 PM

Originally Posted by redchevy
If the rifle is zeroed with both bullets i think I can see HicksHunter's side.

I have fired slower/heavier rounds out of a rifle that impacted higher at 100 yards than lighter faster bullets in the same rifle when the rifle was not individually zeroed.

My factory rem 180 grain 30-06 is zeroed at 100 yards. It is on the fall at 100 yards. It has a zero at appx 50 and 100 yards.


Back to the point the harmonics changed due to heavier bullets with a diff powder charge. What is indeterminable is measuring where the node is. You would have to replicate the exact harmonics to prove/disprove hicks theory which to me cant be done.
Posted By: Smokey Bear

Re: POI of heavier vs. lighter bullets - 01/26/21 11:35 PM

Ok Hicks, run your test this way and tell me what you come up with:
Same gun. Light fast bullet first. Zero at 25 yards. Now shoot it at 100.
Same gun. Slow heavy bullet second. Zero at 25 yards. Now shoot it at 100.
They are both starting out at the same poi before any drop occurs. If there is a difference in trajectory it will be apparent. Post your results and get back to us.
Posted By: HicksHunter

Re: POI of heavier vs. lighter bullets - 01/26/21 11:41 PM

Originally Posted by Smokey Bear
Ok Hicks, run your test this way and tell me what you come up with:
Same gun. Light fast bullet first. Zero at 25 yards. Now shoot it at 100.
Same gun. Slow heavy bullet second. Zero at 25 yards. Now shoot it at 100.
They are both starting out at the same poi before any drop occurs. If there is a difference in trajectory it will be apparent. Post your results and get back to us.


Unfortunately this is a different test under different conditions than OP was using. OP's question is essentially around firing two separate loads without changing point of aim/zeroing.
Posted By: HicksHunter

Re: POI of heavier vs. lighter bullets - 01/26/21 11:47 PM

Originally Posted by cxjcherokec
Originally Posted by redchevy
If the rifle is zeroed with both bullets i think I can see HicksHunter's side.

I have fired slower/heavier rounds out of a rifle that impacted higher at 100 yards than lighter faster bullets in the same rifle when the rifle was not individually zeroed.

My factory rem 180 grain 30-06 is zeroed at 100 yards. It is on the fall at 100 yards. It has a zero at appx 50 and 100 yards.


Back to the point the harmonics changed due to heavier bullets with a diff powder charge. What is indeterminable is measuring where the node is. You would have to replicate the exact harmonics to prove/disprove hicks theory which to me cant be done.


This is true. Because harmonics behave somewhat strangely, one can't say with any confidence that they have been eliminated. However, the shift in POI, rather than just group size, is so minimal as to be pointless within this discussion.

Like I mentioned earlier, how does one's load testing behave when you shoot a series of increasing powder charges? They don't string randomly up and down throughout the series of charges despite the harmonics of the barrel certainly changing. They behave very predictably, especially at close ranges. After all, why is ladder testing mostly pointless at 100 yards?
Posted By: wp75169

Re: POI of heavier vs. lighter bullets - 01/27/21 12:06 AM

Hicks I admit it could be me, but one of us is not understanding something here.
Posted By: HicksHunter

Re: POI of heavier vs. lighter bullets - 01/27/21 12:13 AM

Originally Posted by wp75169
Hicks I admit it could be me, but one of us is not understanding something here.


grin

It's definitely gotten a bit esoteric.
Posted By: J.G.

Re: POI of heavier vs. lighter bullets - 01/27/21 12:16 AM

Originally Posted by HicksHunter
Like I mentioned earlier, how does one's load testing behave when you shoot a series of increasing powder charges? They don't string randomly up and down throughout the series of charges despite the harmonics of the barrel certainly changing. They behave very predictably, especially at close ranges. After all, why is ladder testing mostly pointless at 100 yards?


Well they can string randomly up and down.

And they can behave unpredictable. Even at 100 yards.

Have you load tested a rifle before? Or is all your stance based off of theory? Did you vote for Biden because he said he was going to make things better?
Posted By: HicksHunter

Re: POI of heavier vs. lighter bullets - 01/27/21 12:19 AM

Originally Posted by FiremanJG
Originally Posted by HicksHunter
Like I mentioned earlier, how does one's load testing behave when you shoot a series of increasing powder charges? They don't string randomly up and down throughout the series of charges despite the harmonics of the barrel certainly changing. They behave very predictably, especially at close ranges. After all, why is ladder testing mostly pointless at 100 yards?


Well they can string randomly up and down.

And they can behave unpredictable. Even at 100 yards.

Have you load tested a rifle before? Or is all your stance based off of theory? Did you vote for Biden because he said he was going to make things better?


I'd hate to shoot your spaghetti noodle barreled rifle or awful loads if you're seeing multiple inches of POI shift at 100 yards.
Posted By: Smokey Bear

Re: POI of heavier vs. lighter bullets - 01/27/21 12:28 AM

Originally Posted by HicksHunter
Originally Posted by Smokey Bear
Ok Hicks, run your test this way and tell me what you come up with:
Same gun. Light fast bullet first. Zero at 25 yards. Now shoot it at 100.
Same gun. Slow heavy bullet second. Zero at 25 yards. Now shoot it at 100.
They are both starting out at the same poi before any drop occurs. If there is a difference in trajectory it will be apparent. Post your results and get back to us.


Unfortunately this is a different test under different conditions than OP was using. OP's question is essentially around firing two separate loads without changing point of aim/zeroing.


For the OP, it is a crap shoot where a different load will shoot in comparison to your tried and true old favorite until you shoot it. If it groups well enough to suit you, make note of the difference in poi and you can seamlessly change loads back and forth by making the known adjustments to your sights. With today’s lack of available ammunition, lots of shooters are faced with changing loads out of necessity.

Hicks,
Yes and what I suggested will prove that your logic is incorrect. If you don’t understand why I suggested that, study on it some. With all due respect Hicks, there is a lot of experience weighing in on this thread. Too many here that have worked up and shot too many loads, light and heavy, slow and fast, in too many rifles, to not know better than to agree with what you are suggesting. First hand experience is being freely shared with you by several in this thread.
Posted By: bjh

Re: POI of heavier vs. lighter bullets - 01/27/21 12:36 AM

Originally Posted by cxjcherokec
Here is a real world experience Hicks, proving its harmonics. My sons 6.5CM prints a 0 with 140gr AMAX. Put on the AAC can and note there is a POI shift 1" lower than w/o. MV stayed the same, same lot, same bullet, everything is 100% the same minus adding the can. THAT proves harmonics, without a doubt.


That just you put weight on the barrel and it is shooting low because of the weight.
Posted By: J.G.

Re: POI of heavier vs. lighter bullets - 01/27/21 01:05 AM

Originally Posted by HicksHunter
Originally Posted by FiremanJG
Originally Posted by HicksHunter
Like I mentioned earlier, how does one's load testing behave when you shoot a series of increasing powder charges? They don't string randomly up and down throughout the series of charges despite the harmonics of the barrel certainly changing. They behave very predictably, especially at close ranges. After all, why is ladder testing mostly pointless at 100 yards?


Well they can string randomly up and down.

And they can behave unpredictable. Even at 100 yards.

Have you load tested a rifle before? Or is all your stance based off of theory? Did you vote for Biden because he said he was going to make things better?


I'd hate to shoot your spaghetti noodle barreled rifle or awful loads if you're seeing multiple inches of POI shift at 100 yards.



I shoot all kinds of people's rifles.
And my loads are top of the line.
This was a test load yesterday with a cross wind. The owner of this rifle was quite happy about it.
The Proof Research barrel gets a tad hot at the third rounds and slings it a bit. Happened every time.

[Linked Image]

But please continue to feel you are educating us. And now you have FINALLY moved to insults.

You lose.
Posted By: HicksHunter

Re: POI of heavier vs. lighter bullets - 01/27/21 01:08 AM

Originally Posted by FiremanJG
Originally Posted by HicksHunter
Originally Posted by FiremanJG
Originally Posted by HicksHunter
Like I mentioned earlier, how does one's load testing behave when you shoot a series of increasing powder charges? They don't string randomly up and down throughout the series of charges despite the harmonics of the barrel certainly changing. They behave very predictably, especially at close ranges. After all, why is ladder testing mostly pointless at 100 yards?


Well they can string randomly up and down.

And they can behave unpredictable. Even at 100 yards.

Have you load tested a rifle before? Or is all your stance based off of theory? Did you vote for Biden because he said he was going to make things better?


I'd hate to shoot your spaghetti noodle barreled rifle or awful loads if you're seeing multiple inches of POI shift at 100 yards.



I shoot all kinds of people's rifles.
And my loads are top of the line.
This was a test load yesterday with a cross wind. The owner of this rifle was quite happy about it.
The Proof Research barrel gets a tad hot at the third rounds and slings it a bit. Happened every time.

[ig]https://texashuntingforum.com/forum...-10697-277638-img_20210125_143012331.jpg[/img]

But please continue to feel you are educating us. And now you have FINALLY moved to insults.

You lose.


I was only responding in kind.

You still haven't provided any theoretical bais or real-world results that can explain this at close ranges. Although you're obviously stubborn enough not to try something despite ballistic calculators and the advice of another shooter, I do hope you'll give it a shot sometime in the future.
Posted By: GLC

Re: POI of heavier vs. lighter bullets - 01/27/21 01:37 AM

Originally Posted by HicksHunter
Originally Posted by cxjcherokec
Originally Posted by redchevy
If the rifle is zeroed with both bullets i think I can see HicksHunter's side.

I have fired slower/heavier rounds out of a rifle that impacted higher at 100 yards than lighter faster bullets in the same rifle when the rifle was not individually zeroed.

My factory rem 180 grain 30-06 is zeroed at 100 yards. It is on the fall at 100 yards. It has a zero at appx 50 and 100 yards.


Back to the point the harmonics changed due to heavier bullets with a diff powder charge. What is indeterminable is measuring where the node is. You would have to replicate the exact harmonics to prove/disprove hicks theory which to me cant be done.


This is true. Because harmonics behave somewhat strangely, one can't say with any confidence that they have been eliminated. However, the shift in POI, rather than just group size, is so minimal as to be pointless within this discussion.

Like I mentioned earlier, how does one's load testing behave when you shoot a series of increasing powder charges? They don't string randomly up and down throughout the series of charges despite the harmonics of the barrel certainly changing. They behave very predictably, especially at close ranges. After all, why is ladder testing mostly pointless at 100 yards?

Actually they do string quite a bit at even at 100 yards. Here is 9 loads from 36.9 to 38 grains of powder. I could not find a good node in this powder range.
[Linked Image]

Posted By: wp75169

Re: POI of heavier vs. lighter bullets - 01/27/21 01:49 AM

Damn I’m glad you found one GLC. I looked back and had deleted all mine.
Posted By: GLC

Re: POI of heavier vs. lighter bullets - 01/27/21 02:34 AM

Originally Posted by wp75169
Damn I’m glad you found one GLC. I looked back and had deleted all mine.

smile
Posted By: Bee'z

Re: POI of heavier vs. lighter bullets - 01/27/21 02:39 AM

Wp I do appreciate the name for that load. I am still LMAO clap
Posted By: wp75169

Re: POI of heavier vs. lighter bullets - 01/27/21 03:16 AM

Originally Posted by 2Beez
Wp I do appreciate the name for that load. I am still LMAO clap



That load is well named. I did load development on a new barrel the day before the match, took the best of, loaded a bunch of them and rocked on. I’ve since been losing spectacularly, but the good news is my barrel has sped up significantly so I’m going to start over. Probably the day before the next match.
Posted By: Bee'z

Re: POI of heavier vs. lighter bullets - 01/27/21 03:54 AM

Originally Posted by wp75169
Originally Posted by 2Beez
Wp I do appreciate the name for that load. I am still LMAO clap



That load is well named. I did load development on a new barrel the day before the match, took the best of, loaded a bunch of them and rocked on. I’ve since been losing spectacularly, but the good news is my barrel has sped up significantly so I’m going to start over. Probably the day before the next match.


Se are on the same prior poor planning stage per se lol. I do not know what TF I am going to do if I can even make it,.
Posted By: wp75169

Re: POI of heavier vs. lighter bullets - 01/27/21 03:47 PM

Hey Hicks, please explain GLCs picture.
Posted By: GLC

Re: POI of heavier vs. lighter bullets - 01/27/21 04:05 PM

Found another old one that did not work.[Linked Image]
[Linked Image]
Posted By: ETexas Hunter

Re: POI of heavier vs. lighter bullets - 01/27/21 04:46 PM

popcorn
Posted By: wp75169

Re: POI of heavier vs. lighter bullets - 01/28/21 05:58 PM

Hicks I know you’re probably working so I’ll keep this thread on the first page until we can continue our conversation.
Posted By: HWY_MAN

Re: POI of heavier vs. lighter bullets - 07/04/21 02:39 PM

Hick's I'm going to take a shot at this and we might both be going in the same direction. I'm not talking about harmonics or barrel whip, simple action and reaction. A 308 sighted with a 150 grain and then shooting 175's through the same rifle with no adjustment, and let say there's a 200 fps difference with the 175 being the slowest.
Most likely the 175 will generate more recoil, not much but noticeable. Recoil starts the moment that bullet starts to move and the longer that bullet stays in the barrel the longer that force is felt. The response to that against a person sitting on a bench would be a push back and vertical. With a rifle sighted in at 100 yards with a 150 grain bullet it only makes sense to me that the heavier bullet would naturally tend to print higher given the forces involved. If we could take the shooter completely out of the equation and lock the action in where there was no possible movement my guess would be the heavier load printing slightly lower. I say it's just simply a matter of reaction to the forces generated.

Now lets reverse that and sight the same rifle in with the 175's and what we'll see is just the opposite with the 150's tending to print lower but through a locked down action where we take the human response out it will print higher. Again I say it's the human factor that comes into play.
Posted By: J.G.

Re: POI of heavier vs. lighter bullets - 07/04/21 04:56 PM

Has that been your experience with powder charge, and seating depth testing?
Posted By: HWY_MAN

Re: POI of heavier vs. lighter bullets - 07/04/21 07:01 PM

Originally Posted by FiremanJG
Has that been your experience with powder charge, and seating depth testing?


No Sir! This has been my experience with physic's and the variables that come into play. A basic law is "for every action there is an equal but opposite reaction" and with that reaction come known responses, or at least predictable responses. Now if I slow the 175 down to where both have the exact same amount of recoil, the 175 will still spend more time in the barrel and distribute it's energy over a broader time duration meaning more force on the shoulder over a longer period before the bullet actually leaves the barrel, causing a rise in the barrel. Charge and seating depth have nothing to do with what I'm suggesting, it's simply an action, a response, a result, and this is all on the shooter.
Posted By: Smokey Bear

Re: POI of heavier vs. lighter bullets - 07/04/21 07:09 PM

I 100% agree with barrel harmonics crowd here. Only after both loads have been zeroed and shot at the same distance can trajectory out of the same barrel be compared with any meaningful conclusions drawn.
Posted By: HWY_MAN

Re: POI of heavier vs. lighter bullets - 07/04/21 07:14 PM

Quote
Contrary to popular belief, it has nothing to do with the gun's recoil. The bullet is already long gone by the time the gun is moving backwards.


You trying to say the bullet magically has some type of delayed reaction? That's just not possible, the moment that bullet starts moving it creates an opposite reaction. Now I understand it's over a very minute time frame but it puts actions into motion Immediately.
Posted By: HWY_MAN

Re: POI of heavier vs. lighter bullets - 07/04/21 07:23 PM

Originally Posted by Smokey Bear
I 100% agree with barrel harmonics crowd here. Only after both loads have been zeroed and shot at the same distance can trajectory out of the same barrel be compared with any meaningful conclusions drawn.


You're saying both have been zeroed but the OP is saying only one has been zeroed. The whole reason behind his post is based on what happens when a heavier round that hasn't been zeroed is fired behind a lighter round that has. The heavier round whether right or left will still tend to print higher than the lighter round.
Posted By: J.G.

Re: POI of heavier vs. lighter bullets - 07/04/21 08:23 PM

Originally Posted by HWY_MAN
Originally Posted by FiremanJG
Has that been your experience with powder charge, and seating depth testing?


No Sir! This has been my experience with physic's and the variables that come into play. A basic law is "for every action there is an equal but opposite reaction" and with that reaction come known responses, or at least predictable responses. Now if I slow the 175 down to where both have the exact same amount of recoil, the 175 will still spend more time in the barrel and distribute it's energy over a broader time duration meaning more force on the shoulder over a longer period before the bullet actually leaves the barrel, causing a rise in the barrel. Charge and seating depth have nothing to do with what I'm suggesting, it's simply an action, a response, a result, and this is all on the shooter.


Ok, I'm basing my argument on shooting hundreds of rifles, and thousands of cartridge, bullet, powder combinations.

Harmonica are what cause POI shift. End of story. I can provide lots of photos to prove it. 100 yard to 700 yard paper. Ladder tests from 300 to 700 yards. I can make a heavy bullet hit high or hot low. I can make a light bullet hit high or hit low, by varying the powder charge or by varying the seating depth. Charge and seating depth have everything to do with it.

You're speculating based on no experience with the topic. I am telling you why things happen based on tons of experience with the topic. I am waiting on a .308 barrel to cool right now. My third .308 to load test for in the last 6 days. And every one of them have been loaded with a different make, model, and weight of bullet.
Posted By: J.G.

Re: POI of heavier vs. lighter bullets - 07/04/21 08:23 PM

Originally Posted by HWY_MAN
Originally Posted by Smokey Bear
I 100% agree with barrel harmonics crowd here. Only after both loads have been zeroed and shot at the same distance can trajectory out of the same barrel be compared with any meaningful conclusions drawn.


You're saying both have been zeroed but the OP is saying only one has been zeroed. The whole reason behind his post is based on what happens when a heavier round that hasn't been zeroed is fired behind a lighter round that has. The heavier round whether right or left will still tend to print higher than the lighter round.



And it might print lower. There are almost no "always" in this game. It is as risky a word as "never".
Posted By: HWY_MAN

Re: POI of heavier vs. lighter bullets - 07/04/21 09:33 PM

Originally Posted by FiremanJG
Originally Posted by HWY_MAN
Originally Posted by FiremanJG
Has that been your experience with powder charge, and seating depth testing?


No Sir! This has been my experience with physic's and the variables that come into play. A basic law is "for every action there is an equal but opposite reaction" and with that reaction come known responses, or at least predictable responses. Now if I slow the 175 down to where both have the exact same amount of recoil, the 175 will still spend more time in the barrel and distribute it's energy over a broader time duration meaning more force on the shoulder over a longer period before the bullet actually leaves the barrel, causing a rise in the barrel. Charge and seating depth have nothing to do with what I'm suggesting, it's simply an action, a response, a result, and this is all on the shooter.


Ok, I'm basing my argument on shooting hundreds of rifles, and thousands of cartridge, bullet, powder combinations.

Harmonica are what cause POI shift. End of story. I can provide lots of photos to prove it. 100 yard to 700 yard paper. Ladder tests from 300 to 700 yards. I can make a heavy bullet hit high or hot low. I can make a light bullet hit high or hit low, by varying the powder charge or by varying the seating depth. Charge and seating depth have everything to do with it.

You're speculating based on no experience with the topic. I am telling you why things happen based on tons of experience with the topic. I am waiting on a .308 barrel to cool right now. My third .308 to load test for in the last 6 days. And every one of them have been loaded with a different make, model, and weight of bullet.


The problem is you misunderstood the OP's question, it's simple and the answer is simple. All your experience does little if you don't understand the question and the simple physic's behind the answer. The answer to the OP's question is the shooters reaction to going from a 150 grain bullet to a 175 grain bullet and the increased recoil. You're over thinking this and really trying to complicate it.
Posted By: J.G.

Re: POI of heavier vs. lighter bullets - 07/04/21 09:55 PM

I'm not over thinking. He wanted to know why the heavier bullet happened to impact higher. I explained it.

It would be exactly the same explanation as if he asked why the heavier bullet impacted lower.

Same answer, barrel harmonics.

I do not have shooter reaction, I can't if I'm load testing or obtaining data to 800 yards. You've got to shoot perfect. And I've seen heavy bullets and light bullets shift impact with powder charge change. He is bound by factory ammo in this question, he has no idea what powder charge is within each ammo type. SAAMI spec ammo is built to probably shoot ok in most rifles chambered in the cartridge. Many people will praise an ammo type, and just as many will curse its' name. The ones that hate it have a rifle barrel that powder charge does not agree with. The ones that love it have a rifle barrel that powder charge does agree with. That is all harmonics. The same story makes ammo shift one way or another at X yards.
Posted By: Smokey Bear

Re: POI of heavier vs. lighter bullets - 07/04/21 11:18 PM

Hwy, when you change loads, it’s a bit of a crap shoot which way the POI may move, regardless of how well they shoot. This is a good example: pictures are a few years old but have been saved for future reference. I had been doing some hunting load development with my 7RM. The first target was a 140 Accubond load. The load was known to shoot well and the rifle had been zeroed at 200 yards with this load. Scope remained zeroed for this load during load work ups. The rifle is a pretty accurate 700. The action and locking lugs have been squared away. It is properly bedded. The barrel is floated. The trigger is good. The rifle does not suffer from any weaknesses to blame POI shifts on and all loads are slightly below a maximum charge. Hopefully the pictures illustrate that the direction of POI shifts due to load changes are often a complete surprise the first time they are shot.
[Linked Image]
The Second load is with VV N-165. All other components remained the same. It shoots well also. Note the change in POI. The weight of the projectile has nothing to do with the POI moving nor does it reflect trajectory. It is harmonics and the difference is significant.
[Linked Image]
The third target reflects a load workup with a 150 grain bullet. Again the rifle is still zeroed to the first group pictured. The bullet here is 10 grains heavier than the first two. The rifle shoots it exceptionally well. The POI here moved substantially low and left. Again the big shift in POI gives no indication of the trajectory. Instead it is an expression of harmonics. In my experience, effect on POI when changing up a load is unpredictable.
[Linked Image]

These are three loads that shoot 1/2 MOA or better in the same rifle. Recoil did not impact the POI shifts and the heavier bullet did not impact higher. Once data points are gathered and verified, reliable corrections can be made when swapping loads, assuming your scope tracks true. Prior to shooting, it is a crap shoot how a load change will impact POI.
Posted By: J.G.

Re: POI of heavier vs. lighter bullets - 07/04/21 11:31 PM

Great job Smokey Bear!

Perfect examples of what we've been talking about!
Posted By: bjh

Re: POI of heavier vs. lighter bullets - 07/05/21 11:04 PM

Well Smokey you and JG have it exactly right !!!!! Being a hunter and benchrest shooter i always work with harmonics. But it is easier with B/R since our rifles use a flat bottom stock on the foreand bottom of the stock. They are parrallel to each other and have 2 oz. triggers. This takes the hunter out of the picture except to read the flags and touch the trigger, Have hunted all my life since 7 yrs. old and was blessed with a dad and grand pa who were gun nuts and worked on their own guns . Did their own bedding and trigger work . Hand loaded rifles and and shot guns.
They passed all their knowledge to me and it helped me understand much about firearms!!!
Posted By: J.G.

Re: POI of heavier vs. lighter bullets - 07/06/21 12:19 AM

There are more shooting skills to put a light hunting rifle, or even heavy PRS type rifle on a front bag, or bipod, and look for good results. But it can be done. I much more prefer the strong stock and bipod option.

I have explained it to hundreds of people at my range. I am trying to continue to look through the scope, and watch the bullet hit down range. I don't blink anymore. It was a conscious effort over years and thousands of rounds. Some rifles, it's near impossible to witness impact, even at 300 yards. Some rifles are built to let you watch your bullets fly down range. But shoot them all, like there won't be any recoil. The other direction is the dangerous end. wink
Posted By: J.G.

Re: POI of heavier vs. lighter bullets - 07/06/21 11:42 PM

Guess HWY_MAN is all done trying to educate us with his hypothesis, but lack of experience in the matter.
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