210 berger VLD and Exbal differences

[ultra707]

Hey guys, so I finally found my load after many hours of shooting and went out to do some long range shooting. We first started at 487 yards. Imputed all of my info into Exbal and shot and was right on target. Then moved out to 1011 yards. Imputed all info into Exbal and was right on target. I then moved out to 1357 yards and shot at a rock about the size of a ten inch circle. Shot and was hitting about 12 inches low. I shot again and hit the same spot. I raised 12 inches over the rock and hit it. Shot again and hit the rock. My question is why was Exbal off 12 inches? Is it because I was using G1 BC and that changes with velocity? From what I read, G7 is the better BC to use but Exbal does not allow it. I see Exbal does allow you to input different BC's with lower velocity limits. I asked Berger if they had the bc's for my bullet at different velocitys but Berger just gave me a link to their ballistic calculator online. Does anyone have an estimate of the 210 Berger vlds bc's at lower velocitys?
I'm shooting
300 ultra mag
210 Berger hunting vlds @ 3175 fps
Leupold VX-L with mark 4 m1 turrets
Thanks!
alan

 

[kiwi3006]

Could be a few things. 12" at 1375 is less than a minute of angle (about 0.8 MOA or 3 clicks). It could be that your scope adjustments are not consistent across the full range, not likely with a VX-L but worth checking.
It could also have been some wind etc causing the bullet to drop.
Could also be that you need to validate exbal. Use your data from the 1357 shot and see how it changes the comeups for your 487 and 1011. Read somethingby Shawn Carlock that you should validate at the furtherest range possible.
But look on the brightside, any game within 1000 yds is as good as dead!!

Stu.