I've had no problems whatsoever with any m4 style riffle. I've had two jams in two years with them and thats after not really keeping up with the maintenance... And the thing about jams, is with this series riffle, even if you do get a jam it only takes a few seconds to clear it. I could go for a bigger round but otherwise I'm pretty happy..
we never fire on burst, you're just a hell of a lot more accurate firing in pairs or triplets on semi. And if you really want to, you can crank out a mag on semi pretty darn fast...
some shots of the various riffles ive had/used:
Current riffle w/ 203, peq15, leupold cq/t , foreward pistol grip with taclight, hogue pistol grip, reinforced extractor spring, acuwedge
same as above minus the pitol grip. Had one jam with this setup, during a training cycle where we were going through like 2-300 rounds a day
Old setup, same riffle. Acog, ergo forward pistol grip. Had a pretty nasty double feed once before i switched over to HK mags
my civilian AR. Stag arms, for that pic only my leupold and a harris (the one that swivels)