I don't do this for a living, but I have probably assembled over 50 AR's, maybe more {no B.S.} I have used the "cost effective" carriers as well as the hi-dollar ones and never had a problem. I don't get the big deal many guys are making lately about the staking of the carrier key bolts. Many of the carriers I used already had the key installed, many did not. Even the people that sell carriers seem to really make a big deal that the carrier "has the key already installed", as if it is some nearly impossible feat of mechanical accomplishment to put two Allen screws in a part and tighten them????? I have seen guys at gun shows not buy a carrier because the key was not already installed. I have to ask, if you cant or are too afraid to put in two screws and make them tight and then {oh my god get ready for this one!!!!!} take a hammer and mash a little metal over to help you believe it wont move, what are you doing putting the rest of the gun together???????? Will a key coming loose somehow cause a nuclear explosion I don't know about??? Wont the rifle simply short stroke???? That's all I have ever seen a loose key do.
I have never staked a carrier key bolt, ever. Never had a problem. I have used red Loctite on some of them. If the key is installed and the bolts PROPERLY tightened only an Allen wrench will undo them. Obviously a loose Key is a problem...but the question is why was it put on the gun. Seeing staked bolts does not excuse the assembler from checking for proper install...that stupid little stake may not have anything to do with the bolts not being properly tightened to start with. I recommend if you see a loose bolt anywhere on something you are putting together tighten it and move on with the program.