Hoping some of you fellow shooters can answer a few questions? After checking zero from the bench of off front pedestal and rear sand bag. I backed up to 600 yards and shot again one rifle off of my backpack and it shot 1 MOA lower than BulletFlight said, and another rifle was 2 MOA lower off of bipod. Is this typical, should I change zero to allow for field shooting conditions? Am I doing something wrong? Both rifles shot sub MOA from 600 yards, neither rifle does this if I shoot off of a bench at 600 yards. BulletFlight is spot on and so is my G7 range finder from the bench at 600 yards. Any help would be greatly appreciated.