That's a tough sell.......it depends on his DESIRE to become a better shot. I have a 3D shooting buddy who has the EXACT same technique and he'll never live up to his shooting potential because it goes in one ear and right out the other.
Shooting an index style release for target shooting takes more discipline than I possess. I couldn't do it.
A thumb trigger and learning the right way from the start is an excellent suggestion.
If it's not an option be prepared for long growing pains trying to break that habit of mashing with his index finger. It sounds easy enough to correct in theory but if the mindset isn't there and the dsicipline to stay with it you are peeing up a rope.
