rapid fire

I would like your opinion on this, whether this would work in general, and what would be the legality of it. It's somewhat inspired by the Tac-Con 3MR Trigger. Essentially it uses recoil energy to assist trigger reset. Though my design is more of an external addon.

Howdy y'all. I've been shooting my Glock 17 at the range and I am a pretty decent enough shot. I found myself taking my time and really lining up my shots. What is the proper way to train to stay on target while rapid firing? Also, what are some of the proper metrics when shooting rapid...