Lots of good advise in this thread. I've got several AR's and a different trigger in just about all of them. Nothing wrong with mil-spec triggers, but they aren't going to help you put rounds in the same hole. A couple of my AR's wear mil-spec triggers that I cleaned up and they are precisely what those rifles need - a good no nonsense, reliable trigger. My hunting 6.8 has a POF drop in unit - it is good, but not great (but still way lighter and crisper than any mil-spec trigger). My SPR has a CMC drop in unit and it truly is great, I have zero complaints with this trigger.