That being said, I have a Rock River. I have had it since 2007. The first time I shot it, the carrier key came loose. It has jammed many times, but been an okay gun. That being said, the Colts I have shot are exponentially better, tighter, lighter, and feel much better. In American Rifleman's comparison, the Colt's accuracy was nothing short of amazing.
No manufacturer has had 100% reliability out of the box. This is the first time I've ever heard of a RRA carrier key coming loose. I've shot literally hundreds of AR platform rifles to include Colt, RRA, Stag, CMMG, Olympic, DPMS, Spike's, LMT, and Bushmaster.
I've never once experienced any problems with ANY of them, except for recently my son's Stag lefty doesn't like extracting steel cased ammo every once in a while.
I have a circa 1991 Bushmaster that will eat ANYTHING I put in it without fail.
Does that mean Stag is shit and Bushmaster is the Alpha & Omega? No.
It just means that when you make something (anything) there can be manufacturing differences and sometimes you get a lemon.
I'm not a fan of Colt because about a decade ago during the Clinton Administration, they started making non-mil spec parts to pacify the anti-gun people. They also made non-mil spec pins so that you could not put a third party upper on their lower. No other manufacturer caved like Colt. I tried to find a link, but I'll have to ask some of the River Rats to actually find the accurate info.