I shot my M1A for years, then succumbed to the Dark Side. First time I ever fired my new Bushmaster DCM rifle, right out of the box, was at a Highpower match. I shot my best rapid fire scores ever. I shot well over 2000 rounds through that Bushmaster with the stock 2 stage trigger and never had a problem. Having read all the reports of failure (I've never heard a first-hand report....) I always wondered when it was going to crater, so I sold it on ARFCOM for 50 bucks and put in the RRA.
These days, seems that DCM rifles aren't popular, though ANYTHING AR related is at a premium. There's great advice above my post, but if you're just starting out, don't be afraid of scoring a good used DCM upper to mate to anybody's lower with a RRA 2 stage trigger in it. It'll shoot (damned near) as good as anything out there for a whole lot less $$. Point is: Get out there and shoot! H.