here is an interesting article about useing pistols for fixing your trigger squeeze.
Far Out Shooting: Fixing Your Trigger Squeeze
Far Out Shooting: Fixing Your Trigger Squeeze
I've found that when I'm right on the point of firing that focusing intensely on and concentrating only on the centre of the reticle and nothing else makes the trigger to release occur as a surprise every time.
It's nice and simple and works for me. Maybe give it a try.
Cheers,
Matt