More truing frustrations

holdstillplease

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After 30-40 rounds chrono'd across both Magnetospeed and Labradar, I got an average MV of 2837 for my hand loads with the Hornady 88gr ELD-Match bullet.

Shooting in a local match, I was missing by a country mile. After spotting some misses and eventually figuring out where I was hitting at various distances, I was getting a trued MV of 2707. I also ended up adjusting my BC a bit, dropping from .274 G7 to .260. At that point, the calculator's numbers were resulting in hits more regularly.

I've used the same chronographs for other rounds and not had such large discrepancies, so I think they're trustworthy. My LR reads about 10 fps higher than the MS, but both have given consistent results. This new bullet/cartridge/rifle seems to have much slower DOPE than the chronographs suggest, and that's the part I don't understand yet.

I honestly don't know if I'm just ranting or asking a question. I guess I'd love an explanation, or solution, to why such a large discrepancy would happen. I'm not happy with 2707 fps but was happy with 2837, so I'm frustrated that this whole project was a waste of time and effort, or at the very least I have to start over on my load development.
 

Rlovato

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Im still pretty new at this but seems to me if both your ms and labradar are reading consistant to each other i would assure your mv is correct and the issue is the stated bc of the projectiles which always seem to be inflated
 

Kobyashi72

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Need more information. Could you post your recorded results. (from your Load development) and what your results were from the local match And the inputs you entered in the software.

Have you shot the current 2707 fps configuration on the same range you developed the load for since the local match? Does it still lineup?
 

TheGerman

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I'm going to doubt your velocity is off that much if you checked it with 2 separate things unless something has changed:

- What was the temperature and DA when you ran the chrono and what was the temperature and DA when you were shooting at the match?

- Does your scope 100% track? Depending on the distance, if you are not accounting for scope click differences, they can add up quick.

- Did you have a suppressor on at one point, and removed it?

It can also be a mix of temp difference (what powder?), scope tracking, BC being off that add up to your error. Other than that, its something that is in your ballistics app that isn't entered correctly.
 
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Lowlight

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Always true the BC before changing the MV the software truing that changes the muzzle velocity is the problem.

You true the BC at 800 then make much smaller tweaks to MV to balance the curve out

Changing the BC doesn’t bend the shorter ranges as much, like the MV does.
 

holdstillplease

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Need more information. Could you post your recorded results. (from your Load development) and what your results were from the local match And the inputs you entered in the software.

Have you shot the current 2707 fps configuration on the same range you developed the load for since the local match? Does it still lineup?
8/12 unsuppressed, about 70-75F temp, same shots recorded from both chronos at the same time
LR:

2836
2844
2834
2845
2834

MS v3:
2830
2833
2822
2833
2825

9/15 suppressed, about 45-50F temp, morning of match
LR:
2804
2799
2802

I haven't had time to shoot this rifle since the match.

I'm going to doubt your velocity is off that much if you checked it with 2 separate things unless something has changed:

- What was the temperature and DA when you ran the chrono and what was the temperature and DA when you were shooting at the match?

- Does your scope 100% track? Depending on the distance, if you are not accounting for scope click differences, they can add up quick.

- Did you have a suppressor on at one point, and removed it?

It can also be a mix of temp difference (what powder?), scope tracking, BC being off that add up to your error. Other than that, its something that is in your ballistics app that isn't entered correctly.
I wish I were detailed enough to have good answers for that. The match started out cooler than the last time I chrono'd but then got very hot in the afternoon. I haven't tested the scope tracking, not sure I'd have an accurate way to do that, but it's a Mark 5 HD 3.6-18. Suppressor seems to have reduced MV by about 25 fps which is noticeable but doesn't account for the entire drop.

Always true the BC before changing the MV the software truing that changes the muzzle velocity is the problem.

You true the BC at 800 then make much smaller tweaks to MV to balance the curve out

Changing the BC doesn’t bend the shorter ranges as much, like the MV does.
Excellent point Frank. I wasn't off on the wind too much, so I didn't think to true the BC first because I was focussed on bullet drop. I definitely need to go back to Pawnee for better real-world dope.

I tested bullet drops at 700 and 820 on the 8/12 range session using the published .274 G7 BC and my measured 2830 fps MV, and they were pretty close so I thought I was good for the match. All these loads were from the same batch, RL16 measured on ADI auto trickler setup.
 

Kobyashi72

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Do you have the inputs from your solver?
Was the match held at Pawnee or a different location?
What range did you miss at? What range/drop did you True the MV?
 

Skookum

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8/12 unsuppressed, about 70-75F temp, same shots recorded from both chronos at the same time
LR:

2836
2844
2834
2845
2834

MS v3:
2830
2833
2822
2833
2825

9/15 suppressed, about 45-50F temp, morning of match
LR:
2804
2799
2802

I haven't had time to shoot this rifle since the match.



I wish I were detailed enough to have good answers for that. The match started out cooler than the last time I chrono'd but then got very hot in the afternoon. I haven't tested the scope tracking, not sure I'd have an accurate way to do that, but it's a Mark 5 HD 3.6-18. Suppressor seems to have reduced MV by about 25 fps which is noticeable but doesn't account for the entire drop.



Excellent point Frank. I wasn't off on the wind too much, so I didn't think to true the BC first because I was focussed on bullet drop. I definitely need to go back to Pawnee for better real-world dope.

I tested bullet drops at 700 and 820 on the 8/12 range session using the published .274 G7 BC and my measured 2830 fps MV, and they were pretty close so I thought I was good for the match. All these loads were from the same batch, RL16 measured on ADI auto trickler setup.
The easiest way to figure this out, is to shoot your loads at 500 yards on a day when it is overcast, or early in the morning. That will tell you if your speed is spot on. The way you tested it, with 2 chrono's...it probably is.

Beyond that, shoot for dope at 800 yards and 1000 yards in a NO MIRAGE CONDITION, and adjust BC to match. It doesn't really have to be any harder than that. If you go out and shoot in the middle of the day, all kinds of optical effects can (and probably will) throw your dope off. It isn't a hard process, but attention to detail is imperative.
 
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TheGerman

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8/12 unsuppressed, about 70-75F temp, same shots recorded from both chronos at the same time
LR:

2836
2844
2834
2845
2834

MS v3:
2830
2833
2822
2833
2825

9/15 suppressed, about 45-50F temp, morning of match
LR:
2804
2799
2802

I haven't had time to shoot this rifle since the match.



I wish I were detailed enough to have good answers for that. The match started out cooler than the last time I chrono'd but then got very hot in the afternoon. I haven't tested the scope tracking, not sure I'd have an accurate way to do that, but it's a Mark 5 HD 3.6-18. Suppressor seems to have reduced MV by about 25 fps which is noticeable but doesn't account for the entire drop.



Excellent point Frank. I wasn't off on the wind too much, so I didn't think to true the BC first because I was focussed on bullet drop. I definitely need to go back to Pawnee for better real-world dope.

I tested bullet drops at 700 and 820 on the 8/12 range session using the published .274 G7 BC and my measured 2830 fps MV, and they were pretty close so I thought I was good for the match. All these loads were from the same batch, RL16 measured on ADI auto trickler setup.

Your muzzle velocity like some of us have mentioned isn't the issue. I think your issue is multiple things adding up together; the AB checklist mentions them.

Do you have a Kestrel that reads DA? Very important in regards to the ballistics calculator and matches. I'm suspecting that since the shooting dates were a month apart, under 2 different set of temperatures, there is some error in your DA that translates at range.

I'm also slightly confused as to why, with a suppressor, RL16 (very temperature insensitive), shot roughly 30fps slower. But again, believe what actually happens downrange and make notes of how your bullet/rifle/suppressor/environmental combo perform. I have a spreadsheet specifically for something like this, that I can reference and make profiles in my ballistic program with.

There is a SnipersHide tall target that Frank sells for scope tracking as well as 100 other places that walk you through what to do to test your tracking. If you have a tracking error, this will most definitely be a large/the issue of your clicks not matching what your computer says you should be at.
 

holdstillplease

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Do you have a Kestrel that reads DA? Very important in regards to the ballistics calculator and matches. I'm suspecting that since the shooting dates were a month apart, under 2 different set of temperatures, there is some error in your DA that translates at range.
Yes, I use a 5700 AB LiNK for my primary ballistic calculator. It should handle the DA changes and temp changes just fine.

I'm also slightly confused as to why, with a suppressor, RL16 (very temperature insensitive), shot roughly 30fps slower. But again, believe what actually happens downrange and make notes of how your bullet/rifle/suppressor/environmental combo perform. I have a spreadsheet specifically for something like this, that I can reference and make profiles in my ballistic program with.
I suspect that the chronograph has a part in that discrepancy. The LabRadar is known to have issues triggering off a suppressed shot.

There is a SnipersHide tall target that Frank sells for scope tracking as well as 100 other places that walk you through what to do to test your tracking. If you have a tracking error, this will most definitely be a large/the issue of your clicks not matching what your computer says you should be at.
This is high on my list to check next. Although, once I started getting my MV and BC adjusted to match real-world dope, the scope seemed to give good points of aim during the match, and I was dialing back to zero between stages.
 

DeftSystems

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What is "missing by a country mile?" Ballistics calculators are rarely perfect, so are we talking about a 0.2 mil miss or off by 1.0 mil?

What app are you using?
 

holdstillplease

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What is "missing by a country mile?" Ballistics calculators are rarely perfect, so are we talking about a 0.2 mil miss or off by 1.0 mil?

What app are you using?
One was 8-10 feet low, not sure what the exact angular measurement was. The distance was something like 700 yards, so definitely 1 mil or more.

I was using a Kestrel as well as trying the new Trasol app.
 

djarecke

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One was 8-10 feet low, not sure what the exact angular measurement was. The distance was something like 700 yards, so definitely 1 mil or more.

I was using a Kestrel as well as trying the new Trasol app.
Not to sound derogatory, but what is your shooting ability? Sometimes under the pressure of a clock, our techniques and fundamentals go out the window and we see huge errors that don't make sense.

My recommendation is to true on a range that you're used to without a time clock. I always try to go to a range with a trued gun and good dope under controlled circumstances. Once you do this, you can make very minor adjustments as the day progresses and MV or lighting might change slightly.
 

Kobyashi72

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Did you happen to check if you have a zero shift with the suppressor on vs off?
Your load development was done without a suppressor but you attached the suppressor on the day of the match. You could be hitting low because of the added weight on the end of the barrel.
 

DeftSystems

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One was 8-10 feet low, not sure what the exact angular measurement was. The distance was something like 700 yards, so definitely 1 mil or more.

I was using a Kestrel as well as trying the new Trasol app.
Well, that is roughly 3 mils off. That's a country mile for sure.

I assume these are sustained misses, and not one-offs. My recs:

1. Confirm zero. I have had major zero shifts do to "one-off" mechanical events, such as a ring or base shifting. In my case, an ACOG shifted 48 inches to the right at 200 meters.

2. Try different ballistics apps. I have noted bigger differences between apps than I expected, though not 3 mils worth.

Please keep us updated, I am very curious as to the resolution of this.
 

kthomas

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Something is definitely wrong with your inputs if you are that far off.

My actual dope to my calculated firing solutions are always very close to each other, if not exact. If they are not within 1-2 tenths of a mil, then something I've entered into the software is wrong. I can't remember the last time I've had to "true" MV or BC - it's probably been 2 years.

The Kestrel 5700 with AB is a very accurate tool, but it requires that the user puts in the right inputs.