Some guy at the range shooting next to me, got to yakking between sessions, had similar tastes in AR's, urged me to shoot his M4 with a Gsissele trigger, I was wrapping up for the day so I said what the heck, and shot a few rounds. Until now I have been pretty happy with my RRA trigger, not so happy with the DPMS 308 trigger, now I got to have this trigger in my AR's. I like the 2 stage which this one was, its smooooooth, great break, and good feel on the finger. Which one should I get? They have many different models, can they all fit both guns?