Bullet drop calibration

A

Alaska2006

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Joined
Oct 25, 2015
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Location
Fairbanks, Juneau, Denali
Okay folks I have a question for those schooled in the use of the Kestrel 4500 with AB solver.

I have verified my MV a few dozen times and verified drop at 300 yrd, 600 yrd, 1,000 yrd and yesterday verified at 1,766 just a shade over 1 mile.

Problem I have is my drop at 600 yrds (much easier to deal with environment) gives me a verified drop of 9.68 MOA this is with Berger 215 hybrids/ 300WM with MV of 2,930 fps. elevation of 5,350 above SL, ambient temp. of 59 degrees, Baro PSI 25.56.

My verified drop at 1,000 is 22.72 MOA. for 600 and 1,000 the kestrel solver is very close with actual drop less than 1.00 MOA .
Problem is when I stretch out to 1,766 my Kestrel claims dial up to be 56.48 but my actual required dial up is 58.51.

How do I get a bit more accurate shot solution at long range, or is this within reasonable expectations?

I do have a couple other issues to resolve for my LR shooting. My reloads work very well but at these distances 20-30 fps change in MV is very noticeable. I have a great load worked up but need to work on narrowing my ES.

Even with that some of the loads running a bit faster 2,945 ish still had greater drop than my shot solution was offering.
All MV is verified using lab radar.
Any help will be greatly appreciated.
 
Could be any of many ballistic factors. True zero, actual scope adjustment, low stability, inaccurate scope height, off level/plumb, barrel timing/load development/rest, slope of shots, mirage, magnus, etc.
How accurate is it at 300yds?
 
Rifle is very accurate, if I do my part < .500 MOA @ 300 yrds I frequently practice with clay pigeons @ 600 yrds. and 10" gong at 1,000 yrd.
I just switched my Kestrel for Tmoa to Shooter Moa and that narrowed the adjustment gap at the greater distances.
Understand once you get beyond 1000 everything matters more.
I do run scope level, scope height is correct, true zero bang on 100 yrd.
Front bags were for sure messing with me, I usually don't shoot this far but decided its time to expand my distance a bit and the front bags were a bit too low for my liking.
fairly cool day for Norther NV at 59 degrees but there was slight mirage present at that range didn't notice it at 600 yrd but did further out and higher power.

What has me confused is the AB program being nearly spot on dial up required from 0- 1,000 (less than 1 MOA from actual) but seems about 2 MOA low at 1,766.
 
Coriolis/Eotvos effect?
Do you factor in latitude and azimuth to target?

This may have a little to do with it.

But what I found when shooting my .408 out past 1500/2000/2400 yards was that I needed to use a stepped BC to make things line up. I had to figure this out on my own as the manufacturer only had a set BC number. From certain yardage to yardage .xxx BC worked, then it dropped to .xxx.
This worked in three different states at three different altitudes and three different environments.
 
Last edited:
Alaska2006 said:
Okay folks I have a question for those schooled in the use of the Kestrel 4500 with AB solver.

I have verified my MV a few dozen times and verified drop at 300 yrd, 600 yrd, 1,000 yrd and yesterday verified at 1,766 just a shade over 1 mile.

Problem I have is my drop at 600 yrds (much easier to deal with environment) gives me a verified drop of 9.68 MOA this is with Berger 215 hybrids/ 300WM with MV of 2,930 fps. elevation of 5,350 above SL, ambient temp. of 59 degrees, Baro PSI 25.56.

My verified drop at 1,000 is 22.72 MOA. for 600 and 1,000 the kestrel solver is very close with actual drop less than 1.00 MOA .
Problem is when I stretch out to 1,766 my Kestrel claims dial up to be 56.48 but my actual required dial up is 58.51.

How do I get a bit more accurate shot solution at long range, or is this within reasonable expectations?

I do have a couple other issues to resolve for my LR shooting. My reloads work very well but at these distances 20-30 fps change in MV is very noticeable. I have a great load worked up but need to work on narrowing my ES.

Even with that some of the loads running a bit faster 2,945 ish still had greater drop than my shot solution was offering.
All MV is verified using lab radar.
Any help will be greatly appreciated.
Click to expand...

If you true the 1766 drop to 58.51, how much error does this cause in your shorter range data?
 
I do not calculate latitude or azimuth. In fact not even sure how to do that.
would be interested to learn. I think Coriolis may have played a factor as well. I could see a slight mirage blowing right to left but the wind at the shooting station was left to right and ballistic solver was telling me to correct wind-age to the left. I did not correct wind-age at all on the first round and it hit low right even with the mirage at target indicating a right to left wind. wind at shooting station was light varying 1.5 -2 MPH but no clue what it was at the target. I've not shot much over 1,000 but now I have to figure out the 1 mile. Personal challenge now. Thanks for the thoughts and input
 
Bill 123
I have not tried that to verify but will next trip to the range. Heck It maybe minimal effect at the closer ranges. Good thought and I'll give it a try. I guess best way is jack up the MV in my AB program to match the 1766 yrd drop and see what it does at 600 and 1000.
 
bill123 said:
If you true the 1766 drop to 58.51, how much error does this cause in your shorter range data?
Click to expand...
Alaska2006 said:
Bill 123
I have not tried that to verify but will next trip to the range. Heck It maybe minimal effect at the closer ranges. Good thought and I'll give it a try. I guess best way is jack up the MV in my AB program to match the 1766 yrd drop and see what it does at 600 and 1000.
Click to expand...
ru familiar w the truing feature? Go into gun profile. Tap mv. In there it gives you a suggested range to true at. This will be just short of where the app calculates the bullet going transonic. If it's safe at your range, true to that distance. In the mean time, try the inputting the 1766 drop here and see how close your 300, 600 & 1000 yd drops are.
 
bill123 said:
ru familiar w the truing feature? Go into gun profile. Tap mv. In there it gives you a suggested range to true at. This will be just short of where the app calculates the bullet going transonic. If it's safe at your range, true to that distance. In the mean time, try the inputting the 1766 drop here and see how close your 300, 600 & 1000 yd drops are.
Click to expand...

I do have that feature but not smart enough to use it I guess. I have tried to true at at transonic but the AB program reverts back to 800 yrd after I enter the correction. I may need to you tube the video again to understand the truing part
 
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