Ballistic App Accuracy

[goblbustr]

OK, this is gonna sound nuts. Custom 338 LM, NF ATACR 5-25 x 50 scope 270gr Eldx 2941 fps. Data entered into Applied Ballistics, triple checked data and calculated at a 3 MOA come up for 300 yards. fired 2 rounds 6 inches high. came down 2 clicks fired 3 shot group 1/3 MOA all 4 inches high. My question is how the app (or rifle) can be off this much at 300 yards. The rifles zero at 100yds was checked just prior and all data entered was double checked again and run on a different ballistics' app with the same result up 3 MOA. I stopped shooting after that until I can figure out what's going on. Had I dropped it 4 more clicks to bring it on bull my scope would only be at 1.5 MOA for come up which is definitely not right. Also, the tracking on the scope appears fine as well. What is going on here? Thanks

 

[Chase723]

Post a pic of your zero.

 

[goblbustr]

Post a pic of your zero.

I did not photograph the zero but this is what it looked like

 

[jseandsje]

I'm getting 3 minute as well.

Shoot again at 100 to check 0

Then shoot at 300 uncorrected. Should be 6" low. If not scope.

Hard rest?

 

[Lazy D]

What's your scope height?

 

[tim2446]

OK, this is gonna sound nuts. Custom 338 LM, NF ATACR 5-25 x 50 scope 270gr Eldx 2941 fps. Data entered into Applied Ballistics, triple checked data and calculated at a 3 MOA come up for 300 yards. fired 2 rounds 6 inches high. came down 2 clicks fired 3 shot group 1/3 MOA all 4 inches high. My question is how the app (or rifle) can be off this much at 300 yards. The rifles zero at 100yds was checked just prior and all data entered was double checked again and run on a different ballistics' app with the same result up 3 MOA. I stopped shooting after that until I can figure out what's going on. Had I dropped it 4 more clicks to bring it on bull my scope would only be at 1.5 MOA for come up which is definitely not right. Also, the tracking on the scope appears fine as well. What is going on here? Thanks

only a couple of things zero has to be perfect, fps has to be the right avg. if you are chasing it with a hot barrel fps will be off ! and get off the custom BC that applied ballistic has and dial it in off g7 (AB bc i am not a fan) AB will make you chase FPS and you should know your avg. fps with your garmin or what ever.

 

[yote406]

There are a lot of options when it comes to ballistic calculators. The ones you can get as an app work well for most shooters. I shoot ELR so i run Field Firing Solutions on a Trimble Nomad 900 series hand held. It is a very good system but does require time and effort to learn to use it.

 

[ShtrRdy]

Something else that can make a difference is if the amount of clothing you have on is different and if the rifle support, front and rear, is different from your 'zero' shooting and your 300 yard shooting.

You should really check the tracking on the scope, although Nightforce ATACR are usually very close to be right on.

 

[jseandsje]

You can check but don't believe BC or velocity would be that far off, unless both the BC and velocity values are significantly under valued.

 

[Chase723]

At 300 yards it's only going to be a couple things. At 2900fps you should be ~0.8mils. Scope height can make ~0.1mil diff if you are off by 1/2" on your measurement. With 338 Lapua, rear bag support and making sure it's tracking straight back into you is critical. Easy to get 1MOA of vertical just from that. Eye position/scope shadow asymmetry and parallax can also significantly change POI.

 

[waveslayer]

shooter error might be a factor. What does it group at 100

 

[dfanonymous]

Just because you triple checked your data doesn't mean something isn't afoot with it.

How did you get your muzzle velocity?

BC isn't going to be a big factor this close.

Otherwise I second what @Chase723 said

 

[Lazy D]

And your scope is MOA adjustments and not mills?

 

[FireFlyFishing]

Which calculator are you using?
Perhaps share some screen shots of your inputs.