ABMobile True Up

[Cdixon1]

I had my first chance to shoot some long distance this year, but the AB drops I am getting from ABMobile (and my Fury 5000AB) start deviating from my actual drops past 600 yards (450 and 505 was first round impacts using AB data). I had an experience spotter who help walk me on target to get my actual come ups. Using those, I was able to make consistent hits at all ranges on a 12 inch plate.

Can anyone spot an issue with my input data? Anyway to explain why the 695, 860, and 1001 actual adjustments are so far off? It certainly could be me being a newb, but I just want to make sure nothing jumped out at the more experienced shooters. I am going to try to get back out and confirm again, just haven’t had time yet.


7saum
2912 velocity (magnetospeed)
175 Berger Elite Hunter (.336 G7)
Scope Height 1.3
Zero 1” high at 100
Elv 2650
Station/Absolute Pressure 27.95 (from nearest airport)
Temp 60 degrees

Yardage	AB Drop (MOA)	Actual (MOA)
450	5.6	5.6
505	7.0	7.0
695	12.5	11.0
860	17.9	15.5
1001	23.1	21.5

I certainly appreciate any input, and thank you for your time.

Chris

 

[Sniper1*]

1.3 seems really low for a scope height but that wont have that much affect on those numbers.

Typically you will need to true you DOPE anyway. Looks like you are shooting quite a bit faster than the Magneto is giving you.

As far as AB goes, a lot depends on the wind (AeroD Jump). What's your DOF and Az setting in the program vs real world. Not on of these things will equal the total but start stacking them and your numbers will vary.

 

[Sig Marine]

Have you done a tracking test on your scope? There can be mechanical deviations in your optic that need to be accounted for.

 

[Cdixon1]

1.3 seems really low for a scope height but that wont have that much affect on those numbers.

Typically you will need to true you DOPE anyway. Looks like you are shooting quite a bit faster than the Magneto is giving you.

As far as AB goes, a lot depends on the wind (AeroD Jump). What's your DOF and Az setting in the program vs real world. Not on of these things will equal the total but start stacking them and your numbers will vary.

Yes 1.3 is low. I didn't think it through, and measured to the top of the barrel. It is 1.8 to bore centerline, so I will update that number and run the numbers again. I also agree that increasing the speed to ~3050 did line up much better number/drop wise, but that just seems unrealistic from a 23" barrel 7saum and 175's. I just re-measured velocity saturday, and 2912 is what it gave me.

Have you done a tracking test on your scope? There can be mechanical deviations in your optic that need to be accounted for.

After posting this, this thought hit me. I am using a leupold vx6hd, which unfortunately doesn't have the best reputation. That certainly could be a (major) factor as well. I will see if I can't get this done.

Thanks for the advice.

 

[Lowlight]

You must match the computer to the rifle; you cannot change the rifle to the computer numbers

Truing is a reality; you cannot use what the computer says; you have to tell the computer what the rifle is doing

600 yards, and in, you use Muzzle Velocity to adjust the numbers to match. after 600, you fine-tune with the BC numbers

 

[Rio Precision Gunworks]

Did you change your zero to whatever 1" high is at 100yds??

That's like a 300yd zero.

 

[6.5SH]

Did you change your zero to whatever 1" high is at 100yds??

That's like a 300yd zero.

Even using the offset feature it still didn't line up. He has something else wrong/missing in his data.

 

[Rio Precision Gunworks]

Even using the offset feature it still didn't line up. He has something else wrong/missing in his data.

I'd say it's likely a combination of the 1.3" bore height and not using an offset. Or just the bore height if he did use the offset feature.