A scope that doesn't track true MOA will do it. Need to do a tall target test at 100 yards. MattThis is not a solution. I have seen more guys twirling kestrels at matches like "tactical fidget spinners" and still missing targets. Shooter, JBM, AE, Strelok, Etc, will all give you good data if you if you use them properly.
Also the sight height is not going to effect as much difference as you posted. A bad zero however will screw you up. My money is still on environmental or bad input.