This curious issue reared it ugly head again 2 weeks ago, different cause and gun though. My Winchester Model 12 is stocked slightly too high for me, knew this day I bought it, rather than modify the stock I simply got use to looking over the gun to where I fathomed it was patterning. It worked most of the time, made it a pretty decent gun for the trap field, but couldn't break more than 22 on average on the skeet field with it. Finding this on the annoying side I started getting my face lower on the stock in order to get the right sight picture and shoot it properly, everytime I did, my scores went to hell, could not touch a low house target consitently. One of the resident members figured it out for me, I was shooting 2' behind the targets, everytime I got my face down low enough on the stock for the sight picture to "look" right, my left eye was taking over. Dug out my 870 yesterday, shot 20, 22, 22 in 35 KP/H winds, lost a couple of each round to diving targets.