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#6443489 - 09/08/16 10:04 AM My iStrelok is off on elevation?
ZK-315 Online   content
Pro Tracker

Registered: 10/11/13
Posts: 1560
Loc: Temple...Hunt in Freestone Co.
I need some help troubleshooting a ballistic calculator. I'm running Strelok and I can't get the trajectory to match actual trajectory.

7mm WSM - 1:8 twist
Berger 180 vld hunting
R22
Federal 210 primers

**I haven't chronographed this load yet, but have all of my other inputs correct in the app.** The only change I make is MV to attempt to get the table to match the actual impact of the bullet. I can get them to be the same at specified distances, BUT when I step out to the next distance it's off. My trajectories don't match between the app and the actual shot. Grouping is fine, just elevation is off.

For example, I dial 3.6mils for 750 yards and shoot a few times. Grouping is decent. I mess with the MV in the app to where 3.6mils shows for the 750 yard shot. With the correct MV at 750 yards, my table shows below:
100 - 0
250 - 0.5
500 - 1.9
750 - 3.6
1000 - 5.8

Actual elevation shots:
100 - 0 mils
250 - 0.8 mils
500 - 2.2 mils
750 - 3.6 mils
1000 - 6.1 mils

I can change the speeds in the app to gain the correct elevation at each one of these distances, but then the rest of the distances are off....what gives?? I'm stumped.

I'm still pretty new to this long range shooting, but I have a pretty good idea of the different inputs I need (altitude, BP, Bullet weight, BC, MV, etc). I'm just trying to get the trajectories to match if possible.

Any ideas? Did I input something completely out of whack or what?

**Disclaimer, I did chrony the first set of loads I made up at .5gr increments, so I wasn't just slinging lead downrange completely blind. I picked a MV between two of the .5gr increments that were closest to this load.

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#6443536 - 09/08/16 10:32 AM Re: My iStrelok is off on elevation? [Re: ZK-315]
HicksHunter Offline


Registered: 01/22/09
Posts: 1536
Loc: Kerrville
It probably won't make you feel better, but I'm having the same issues. Here's my 6.5CM table (from Strelok+) with actual results.

So I'm shooting a 140gr amax (BC .585) at 2685 fps, and my rifle is zeroed at 100 yards. Strelok is telling me that I should be dialing these values at certain ranges:

200- .5 mil
300- 1.3 mil
400- 2.1 mil
500- 3.0 mil

I was making very reliable groupings at each range using these values, however:

200- .4 mil
300- .9 mil
400- 1.5 mil
500- 2.5 mil

I've tried fiddling with every variable, finding ballistic calculators where I can input the G7 BC instead of G1, and I just can't get it to line up. I'll be watching this thread to see what sort of input you get. Only explanation I can come to is that my scope isn't tracking correctly. What sort of scope are you using?


Edited by HicksHunter (09/08/16 10:34 AM)

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#6443550 - 09/08/16 10:39 AM Re: My iStrelok is off on elevation? [Re: ZK-315]
FiremanJG Offline
THF Celebrity

Registered: 12/16/08
Posts: 17893
Loc: Wolfe City, TX
Get your MV in the program to match the DOPE for the four that it can match.

The error at 750 yards (ONLY!) is tracking error in the scope. There is no scope that tracks 100% perfect. If the rifle/load/scope shoot the same DOPE every time, you're OK.

Just know about that error, at that point in the turret, for future elevation corrections the program gives you, for different environments.
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#6443552 - 09/08/16 10:40 AM Re: My iStrelok is off on elevation? [Re: HicksHunter]
FiremanJG Offline
THF Celebrity

Registered: 12/16/08
Posts: 17893
Loc: Wolfe City, TX
Originally Posted By: HicksHunter
It probably won't make you feel better, but I'm having the same issues. Here's my 6.5CM table (from Strelok+) with actual results.

So I'm shooting a 140gr amax (BC .585) at 2685 fps, and my rifle is zeroed at 100 yards. Strelok is telling me that I should be dialing these values at certain ranges:

200- .5 mil
300- 1.3 mil
400- 2.1 mil
500- 3.0 mil

I was making very reliable groupings at each range using these values, however:

200- .4 mil
300- .9 mil
400- 1.5 mil
500- 2.5 mil

I've tried fiddling with every variable, finding ballistic calculators where I can input the G7 BC instead of G1, and I just can't get it to line up. I'll be watching this thread to see what sort of input you get. Only explanation I can come to is that my scope isn't tracking correctly. What sort of scope are you using?


Put the BC back to where it was, and adjust MV until the calculator matches known DOPE.
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#6443556 - 09/08/16 10:42 AM Re: My iStrelok is off on elevation? [Re: ZK-315]
ZK-315 Online   content
Pro Tracker

Registered: 10/11/13
Posts: 1560
Loc: Temple...Hunt in Freestone Co.
NF ATACR f1 5-25x56. I've already done a tracking test with it at 100 yards and it did fine.

I see yours is off as well, but when I was out shooting (its been a couple of months now at that long range), I would get at least one of the distances lined up between actual shooting and Strelok. I was pretty consistant at 750 in elevation, so I changed MV on Strelok to where it was at 3.6 mils (actual shooting was 3.6 also) but then none of my other numbers in my table matched the actual shooting. I'm stumped.

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#6443566 - 09/08/16 10:49 AM Re: My iStrelok is off on elevation? [Re: FiremanJG]
ZK-315 Online   content
Pro Tracker

Registered: 10/11/13
Posts: 1560
Loc: Temple...Hunt in Freestone Co.
Originally Posted By: FiremanJG
Get your MV in the program to match the DOPE for the four that it can match.

The error at 750 yards (ONLY!) is tracking error in the scope. There is no scope that tracks 100% perfect. If the rifle/load/scope shoot the same DOPE every time, you're OK.

Just know about that error, at that point in the turret, for future elevation corrections the program gives you, for different environments.


Would that be magnified more at, lets say, higher elevations?

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#6443576 - 09/08/16 10:52 AM Re: My iStrelok is off on elevation? [Re: ZK-315]
FiremanJG Offline
THF Celebrity

Registered: 12/16/08
Posts: 17893
Loc: Wolfe City, TX
No.

If it's got a .3 Mil error at a DA of 1000', it should hold a .3 Mil error at 3000', 6,000' ect.
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#6443592 - 09/08/16 10:56 AM Re: My iStrelok is off on elevation? [Re: ZK-315]
ZK-315 Online   content
Pro Tracker

Registered: 10/11/13
Posts: 1560
Loc: Temple...Hunt in Freestone Co.
up Awesome. Thanks. That puts this into a better perspective to understand. BTW one of these days I can break away on a free weekend, I'll be coming to see you for your class.

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#6443595 - 09/08/16 10:57 AM Re: My iStrelok is off on elevation? [Re: ZK-315]
HicksHunter Offline


Registered: 01/22/09
Posts: 1536
Loc: Kerrville
The closest I can get to matching the dope is if my MV is 2850 fps. Isn't that a little extreme, especially with the relatively mild loading of 41.7gr H4350?

And I chrono'd my loads right before going out to the long range, so I'm not sure what could have happened there. I had an ES of 11 fps, average of 2685. Could the chrono just be that wrong?

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#6443620 - 09/08/16 11:13 AM Re: My iStrelok is off on elevation? [Re: HicksHunter]
FiremanJG Offline
THF Celebrity

Registered: 12/16/08
Posts: 17893
Loc: Wolfe City, TX
Originally Posted By: HicksHunter
The closest I can get to matching the dope is if my MV is 2850 fps. Isn't that a little extreme, especially with the relatively mild loading of 41.7gr H4350?

And I chrono'd my loads right before going out to the long range, so I'm not sure what could have happened there. I had an ES of 11 fps, average of 2685. Could the chrono just be that wrong?


I trust DOPE more than a chronograph, especially an optical chronograph. Is yours an optical?

I have put no less than 4000 140 gr A-maxes down range. Using a G-1 of .585 and an MV of 2800 fps my DOPE is:

200 .4
300 1.0
400 1.8
500 2.6
600 3.6
700 4.5 to 4.7 depending on DA
800 5.6 to 5.8 depending on DA.

I'm doing that with a 25" barrel and 42.8 gr of H-4350. Previous load on a former lot of powder was 42.4 gr H-4350, so lot to lot does vary. Yours just may simply be making more speed with less powder.
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#6443622 - 09/08/16 11:13 AM Re: My iStrelok is off on elevation? [Re: ZK-315]
FiremanJG Offline
THF Celebrity

Registered: 12/16/08
Posts: 17893
Loc: Wolfe City, TX
Originally Posted By: ZK-315
up Awesome. Thanks. That puts this into a better perspective to understand. BTW one of these days I can break away on a free weekend, I'll be coming to see you for your class.


Looks like you've got this figured out, already. smile
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#6443635 - 09/08/16 11:21 AM Re: My iStrelok is off on elevation? [Re: FiremanJG]
ZK-315 Online   content
Pro Tracker

Registered: 10/11/13
Posts: 1560
Loc: Temple...Hunt in Freestone Co.
Originally Posted By: FiremanJG
Originally Posted By: ZK-315
up Awesome. Thanks. That puts this into a better perspective to understand. BTW one of these days I can break away on a free weekend, I'll be coming to see you for your class.


Looks like you've got this figured out, already. smile


Ehhh I don't know if I would say that lol. It's all been kind of self taught with a little help from an extended family member.

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#6443686 - 09/08/16 12:00 PM Re: My iStrelok is off on elevation? [Re: ZK-315]
jeff1383 Offline
Tracker

Registered: 05/19/11
Posts: 873
Loc: Frisco
Have you guys corrected the pre set weather/altitude settings in the app? I had used the Pro version for a while ( not the free one )and it allowed me to make corrections within the app by changing the elevation input. Then it would calculate my estimated MV

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#6443689 - 09/08/16 12:04 PM Re: My iStrelok is off on elevation? [Re: ZK-315]
jeff1383 Offline
Tracker

Registered: 05/19/11
Posts: 873
Loc: Frisco
FWIW I've had more 1st round hits at distance since using a kestrel with applied ballistics. Not saying it's a necessity but it definitely makes life a tad easier

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#6443692 - 09/08/16 12:07 PM Re: My iStrelok is off on elevation? [Re: jeff1383]
FiremanJG Offline
THF Celebrity

Registered: 12/16/08
Posts: 17893
Loc: Wolfe City, TX
I use "Shooter" ballistics on the phone. But when these thing happen with that app, that's what I do to correct it.
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