I would have to lean towards bad shooting habits here. I have seen this before where 4 of us will be at the gun club shooting and one guy shoots a POI completely different than the other 3. Ifa new shooter is shooting an unfamiliar gun the trigger pull/squeeze can be different, and anticipating the recoil is the other newbie mistake. An exagerated version of this can be demonstrated by using a handgun. I attended a handgun seminar at my local range and the Certified trainer there did a funny thing to a guy who had a flinch by handing him an empty gun and watching him flinch even with no round in the chamber. The same can happen to an unfamilar shooter with arifle of substantial recoil.