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#7027892 - 01/06/18 11:22 PM Figuring out Optimal Charge Weight
TackDriver Online   content
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Registered: 05/02/14
Posts: 865
Sometimes I chase my tail chasing accuracy, and I am sure some of you do. I am pretty sure picking the wrong OCW is one of the reasons. When I do a load development, I see ugly groups or three holes but pick the nice one hole group as my go to load but when you see changes of temp, your one hole group is now a 3 shot group. Back to square 1!!
Perhaps you guys can help me with your opinions.

I did two OCW tests today round robin style, top line is the .308 with the IMR4064 and 168 VLD and the bottom line is the 6.5 Creedmoor with H4350 and 140 Hybrids.

If some of you OCW gurus could help me narrow my search for the OCW to pick,,,next will be the jump test. ( Seating depth test )

I looked at the top line on the target which is the .308 and chose #2, 3 and 4 as my OCW.
As for the bottom line on the target which is the 6.5 Creed, I chose #1,2 and 3 as my OCW.

I see those 3 shot groups I picked which are very close on the same line and POI.

Would you guys agree? Of course the jump test is after I pick the middle charge between the 3 groups. What do you guys pick?

I think this is a learning experience most of us could benefit when we do our load developments and learn to read OCW and pick the correct OCW.
[img]https://i.imgur.com/pxhCBiEl.jpg?1[/img]

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#7028080 - 01/07/18 07:24 AM Re: Figuring out Optimal Charge Weight [Re: TackDriver]
FiremanJG Online   content
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Registered: 12/16/08
Posts: 25150
Loc: Wolfe City, TX
.308 Win, 43.0 gr is where I would stay.

6.5 Creedmoor, I would load up to 43.0 gr and see if it gets better. None of those give me the warm fuzzy. 41.3 gr looks best, and I bet that's your low node. Good chance 41.0 would be pretty good, too.

I'm on the same page as you. When one groups very well, I want the charge lower, and the charge higher to have grouped fairly well, also.

Temp changes do not affect how well one groups if one is using a temp stable powder. Of course, even temp stable powders can over-pressure once summer hits, if the load was at max or above.
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#7028182 - 01/07/18 09:01 AM Re: Figuring out Optimal Charge Weight [Re: TackDriver]
Tbar Online   content
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Registered: 10/02/08
Posts: 11075
Originally Posted By: TackDriver
Sometimes I chase my tail chasing accuracy, and I am sure some of you do. I am pretty sure picking the wrong OCW is one of the reasons. When I do a load development, I see ugly groups or three holes but pick the nice one hole group as my go to load but when you see changes of temp, your one hole group is now a 3 shot group. Back to square 1!!
Perhaps you guys can help me with your opinions.

I did two OCW tests today round robin style, top line is the .308 with the IMR4064 and 168 VLD and the bottom line is the 6.5 Creedmoor with H4350 and 140 Hybrids.

If some of you OCW gurus could help me narrow my search for the OCW to pick,,,next will be the jump test. ( Seating depth test )

I looked at the top line on the target which is the .308 and chose #2, 3 and 4 as my OCW.
As for the bottom line on the target which is the 6.5 Creed, I chose #1,2 and 3 as my OCW.

I see those 3 shot groups I picked which are very close on the same line and POI.

Would you guys agree? Of course the jump test is after I pick the middle charge between the 3 groups. What do you guys pick?

I think this is a learning experience most of us could benefit when we do our load developments and learn to read OCW and pick the correct OCW.
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#7028211 - 01/07/18 09:29 AM Re: Figuring out Optimal Charge Weight [Re: FiremanJG]
TackDriver Online   content
Tracker

Registered: 05/02/14
Posts: 865
Originally Posted By: FiremanJG
.308 Win, 43.0 gr is where I would stay.

6.5 Creedmoor, I would load up to 43.0 gr and see if it gets better. None of those give me the warm fuzzy. 41.3 gr looks best, and I bet that's your low node. Good chance 41.0 would be pretty good, too.

I'm on the same page as you. When one groups very well, I want the charge lower, and the charge higher to have grouped fairly well, also.

Temp changes do not affect how well one groups if one is using a temp stable powder. Of course, even temp stable powders can over-pressure once summer hits, if the load was at max or above.


Added the chrono velocities from the test.

.308:
1. 2705-2697-2685
2. 2716-2715-2711
3. 2740-2718-2735
4. 2740-2734-2737
5. 2766-2753-2761
6. 2772-2771-2764
7. 2791-2810-2733

6.5 Creedmoor
1. 2698-2728-2739
2. 2714-2742-2752
3. 2749-2751-2758
4. 2768-2773-2779
5. 2773-2807-2811

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#7028229 - 01/07/18 09:44 AM Re: Figuring out Optimal Charge Weight [Re: TackDriver]
FiremanJG Online   content
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Registered: 12/16/08
Posts: 25150
Loc: Wolfe City, TX
No offense meant when I ask this.

Now that we have chrono data, .308 Win, 42.7 gr looks like a low ES. 6.5 Creedmoor 41.9 gr does as well. Could the worsening of group be shooter error?
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#7028246 - 01/07/18 09:59 AM Re: Figuring out Optimal Charge Weight [Re: TackDriver]
Eyesofahunter Offline
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Registered: 01/11/15
Posts: 632
Loc: Hill Country of Texas
I like the 43.3 for the 308. And the 41.9 for the 6.5.
I always look for the lowest vertical dispersion in the powder charge then tune horizontal with seating depths. I shoot mine at 300 or 400 so the vertical is easier to pick out, but the chrono data with those two look good to me. My 6.5 load is 41.9 aa4350 with a 143 eld-x.

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#7028265 - 01/07/18 10:15 AM Re: Figuring out Optimal Charge Weight [Re: FiremanJG]
TackDriver Online   content
Tracker

Registered: 05/02/14
Posts: 865
Originally Posted By: FiremanJG
No offense meant when I ask this.

Now that we have chrono data, .308 Win, 42.7 gr looks like a low ES. 6.5 Creedmoor 41.9 gr does as well. Could the worsening of group be shooter error?


For the .308, #4 ES is great as well, but picking that charge with #5 next to it is a disaster, see that bad POI shift.

For the 6.5 Creed, the last two is not shooter error, I was pretty much careful with each shot. But trying the 2nd to last group can be done. I do agree that the 41.9 group does look nice with horizontal grouping.

The 6.5 Hybrid is .020" off the lands, single fed and don't fit in the mag, I wanted to see if it shoots better since my last which is the first test shot pretty well ( virgin brass ) with .080" off the lands and fits in the mag. I like testing with fireformed brass. I should pick a OCW and do the seating depth test round robin style. 6.5 Creed has only 115 rounds down the tube.


Edited by TackDriver (01/07/18 10:19 AM)

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#7028275 - 01/07/18 10:20 AM Re: Figuring out Optimal Charge Weight [Re: Eyesofahunter]
TackDriver Online   content
Tracker

Registered: 05/02/14
Posts: 865
Originally Posted By: Eyesofahunter
I like the 43.3 for the 308. And the 41.9 for the 6.5.
I always look for the lowest vertical dispersion in the powder charge then tune horizontal with seating depths. I shoot mine at 300 or 400 so the vertical is easier to pick out, but the chrono data with those two look good to me. My 6.5 load is 41.9 aa4350 with a 143 eld-x.


I would cringe with choosing 43.3 grains. See the next group with bad POI shift. I do agree it has real nice horizontal grouping.


Edited by TackDriver (01/07/18 10:21 AM)

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#7028276 - 01/07/18 10:21 AM Re: Figuring out Optimal Charge Weight [Re: TackDriver]
FiremanJG Online   content
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Registered: 12/16/08
Posts: 25150
Loc: Wolfe City, TX
It's more difficult to help when things are not referred to in charge weight. I keep having to toggle back and forth.
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#7028281 - 01/07/18 10:25 AM Re: Figuring out Optimal Charge Weight [Re: FiremanJG]
TackDriver Online   content
Tracker

Registered: 05/02/14
Posts: 865
Originally Posted By: FiremanJG
It's more difficult to help when things are not referred to in charge weight. I keep having to toggle back and forth.


Side note, I did not have a Type S full sizing bushing die before I loaded those. I used a body die and ran them through a Redding neck sizer with the bushing. The Type S die just came in, would it make a difference if I shot the same loads again with the new die?

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#7028290 - 01/07/18 10:57 AM Re: Figuring out Optimal Charge Weight [Re: TackDriver]
FiremanJG Online   content
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Registered: 12/16/08
Posts: 25150
Loc: Wolfe City, TX
I doubt it. Those dies you already used are no doubt high quality.

Is it possible to test at 200 yards or more?
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#7028306 - 01/07/18 11:18 AM Re: Figuring out Optimal Charge Weight [Re: TackDriver]
Eyesofahunter Offline
Tracker

Registered: 01/11/15
Posts: 632
Loc: Hill Country of Texas
Originally Posted By: TackDriver
Originally Posted By: Eyesofahunter
I like the 43.3 for the 308. And the 41.9 for the 6.5.
I always look for the lowest vertical dispersion in the powder charge then tune horizontal with seating depths. I shoot mine at 300 or 400 so the vertical is easier to pick out, but the chrono data with those two look good to me. My 6.5 load is 41.9 aa4350 with a 143 eld-x.


I would cringe with choosing 43.3 grains. See the next group with bad POI shift. I do agree it has real nice horizontal grouping.


To each his own, that is the load I would run without reservation based on what I have seen so far.

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#7028308 - 01/07/18 11:23 AM Re: Figuring out Optimal Charge Weight [Re: TackDriver]
Buzzsaw Online   content
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Registered: 06/29/11
Posts: 13049
Loc: Frisco, Texas
No offense when I say this, but why are you even asking this? its obvious your gun is a shooter @ 100 yards.

I agree with Jason , you have good "node." now stretch it out and quit wasting bullets and powder banana
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#7028313 - 01/07/18 11:30 AM Re: Figuring out Optimal Charge Weight [Re: FiremanJG]
TackDriver Online   content
Tracker

Registered: 05/02/14
Posts: 865
Originally Posted By: FiremanJG
I doubt it. Those dies you already used are no doubt high quality.

Is it possible to test at 200 yards or more?


I can do that, I'll narrow on the picked charges to .2 increments at 300. See what pops up.

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#7028316 - 01/07/18 11:34 AM Re: Figuring out Optimal Charge Weight [Re: Eyesofahunter]
TackDriver Online   content
Tracker

Registered: 05/02/14
Posts: 865
Originally Posted By: Eyesofahunter
Originally Posted By: TackDriver
Originally Posted By: Eyesofahunter
I like the 43.3 for the 308. And the 41.9 for the 6.5.
I always look for the lowest vertical dispersion in the powder charge then tune horizontal with seating depths. I shoot mine at 300 or 400 so the vertical is easier to pick out, but the chrono data with those two look good to me. My 6.5 load is 41.9 aa4350 with a 143 eld-x.


I would cringe with choosing 43.3 grains. See the next group with bad POI shift. I do agree it has real nice horizontal grouping.


To each his own, that is the load I would run without reservation based on what I have seen so far.


I'll include that charge on the next test at 300 yards soon. If your theory is correct, I'll buy you a burger when I am in town. cheers

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