Lots of great information here. Anyone who’s been shooting for any length of time will deal with a bit of target panic or flinch. The tendency to yank or grab the trigger in anticipation of the explosion is a strong one. Back to the basics. By all means, try the coin trick, also occasionally having a friend load your rifle behind your back so you don’t know if you’re firing a live round, a priming charge only, or an empty rifle. This can be a real eye opener, revealing the extent and severity of any flinches... B.R.A.S.S. has been mentioned and you should also work on building a stable firing platform (your body essentially) volumes have been written on the subject.