Two guns, Sig P220/.45, Berette 92fs. Same thing happens using either gun. When shooting slow fire, nice controlled breathing, smooth clean trigger pull, I tend to shoot left two to four inches of point of aim. Group size is ok. 2-3 at 7 yards, 4-5 at 15 yards, and 6" at 25 yards. Shooting with both hands (right hand strong). Both eyes open. Start shooting cocked in SA mode. But, if I just snap off, say, ten rounds rapid, group sizes get smaller and dead center for where I aim. As far as I can tell I'm getting the same site sight picture and still breathing when shooting rapid. This is more disconcerting than anything, but I would like to correct it. Tried squeezing less with my left hand and more. Doesn't seem to make a difference. FWIW, I do the same thing with a rifle, even when I use a scope. Any suggestions or help would be appreciated.