During my Gunsite Basic Carbine class, everyone had an AR15, M16, or M4 with the exception of two guys who were running AUGs. Both AUG shooters had some problems with the rifles functioning, but they made it through the class. There were two AR problems in that class. One was a guy who had a Bushmaster who had never fired that AR15 or any other AR15 prior to the first day of class. The other gun was a Colt that had the bolt break in half. It was a gun that belonged to Gunsite and who knows how many thousands of rounds had been fired through it.
IMO, bickering between Colt and Bushmaster is an internet exercise. In reality, it doesn't matter. I do have to make one comment however. People with Colts are conviced that they are worth the extra money. I am not saying they are or they are not, but in the several carbine classes I have taken, I have seen several Colts have problems. The people involved seemed to pretend it didn't happen. They just locked that out of their mind. At Gunsite Advanced carbine, a guy that was staying at the same place I was had a Colt and had problems with it more than once during the class. At night, when we were cleaning our rifles, he made a couple comments about my Bushmaster. When I mentioned that I had never had the slightest problem in any class I ever took and he was having daily problems, it all just went over his head. Same thing with the instructors. A few people had some problems with their Colts and the next day the instructors were telling us that they never see problems with Colts. Yet the day before, I had to let an active duty special forces guy use my back-up Bushmaster because his GI issue M4 went down.