What Fastbolt has stated certainly makes sense, but what I would do is shoot from a rest at same distance(15yds) and see if that makes any difference. Also, I find that most indoor ranges are not set up to hang the target for folks over 6'2" to shoot on a level plain of aim to target. What I am saying is that you may have to actually point the pistol down slightly to hit center of target if shooting at silhouette target. Also try shooting at top of target(head if silhouette target) and see if that improves. Sounds fishy I know but if you are using isoceles stance then your point of aim is lowered and it is not a perfect straight line to target, so your are shooting down which can play on your eyesight point of aim. I don't have scientific proof of this theory so this is my own perception of what happens to me when shooting at indoor range I shoot at...zorro49