Went to range to get my data down to get a custom turret. I zero'd in at 200 yards. I chronographed my 300wm 180gr Hornady Superformance SST at an average 3055 fps(the ammo advertises 3130fps with a BC of .48). I shot a mid range group at 500 yards that took 6MOA from Zero'd and a long range group that took 12MOA from zero'd. When I went to validate actual field MOA adjustments in the G7 ballistic calculator, it generated a muzzle velocity of 3224fps, I seem to be dead on at any range with in 700 yards with the new ballistic data plugged into G7 ballistic calculator, but when I attempted to shoot at 850 yards I was way way over target with the recommended 52 clicks. What could be the issue here? Could the velocities really be 3224 fps even through my chronograph gave me a 15 shot average of 3055 fps and the ammo advertised 3130 fps? Any ideas of what I am missing here. I have all my conditions in good.