There is some interesting files here. The most interesting is how to very cheaply and easily improve you nasty, mil spec AR trigger. Believe me, it works and you'll see the improvement right away.
https://www.dropbox.com/sh/cv91ck87v...UI7caNL9a?dl=0
https://www.dropbox.com/sh/cv91ck87v...UI7caNL9a?dl=0