I notice that when dry-firing at home, I am much more stable than in real life at the range. I am convinced that it's a psychological phenomenon -- probably related to impending recoil and blast
. It really disturbs me sometimes too, because I know I can
do it without shaking, but my mind becomes my enemy.
I actually think this is one of the most compelling aspects of the shooting hobby. I'm really fighting against my own limitations, and every time I learn something that makes me better it feels like a real victory.
The comments on gripping too hard may be related too. I don't know if I dry-fire with a looser grip. I should do some experimentation...