Sounds very much like a grip issue to me. I carried G30 & G21 my last ten years as a cop and while I qualified with very high scores, I shot to the left more so than with my 9mm's and .40's. The exception was my G36. I have never had issues along those lines with the 36. I finally took the G21 to Robar and had the grip diameter reduced. End of issue. I have average sized hands and am not intimidated by recoil or large guns. I carried a S&W 629 4inch barreled in .44 magnum as a Sheriff's Deputy in the 80's. But I did go to a rubber (Safariland) smaller diameter grips to accomodate my hand size. I always shot and do shoot well with it today. Since the full size 10mm and .45ACP are the same sized frame, I suspect that you have the same problem I did. I am also getting my G30 grip reduced for the same reason. Most of my Glocks are old original runs, not Gen 3 or Gen 4, so I have to have something that drastic done. I don't recall whether or not you have access to a Ransom Rest to lock the pistol down to confirm it isn't a manufacturing issue. Might be worth taking to a good gun smith with one and find out whether its the gun or the fitting issue.