I would start with the middle of the pad before the first joint. Keep in mind you must squeeze the trigger straight back. Without observing your shooting, I would say you are using the finger to push the trigger to the left instead of straight back. Keep in mind, the finger is moving constantly rearward without any hesitation until the gun fires. There is to be no jerking or anticipation of the shot, just a constant rearward pressure until it goes off. Constant dry fire will help you discern most of the problems encountering trigger press. Practice, Practice, Practice.

Nick

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NRA Instructor\GCA Gunsmith