Just trying to find out what's going on here.   My colt bolt carrier is causing short stroking.   I know it's not the bolt/rings as I've put it in a different carrier and it cured the problem.   Tried the carrier in a midlength carbine and it shortstroked there too with the different bolt.    Definitely in the carrier.    The key is staked and tight, I sprayed gunscrubber through the key and all gas passages are apparently clean.    This carrier was fine for the last few thousand rounds fired through it.   What the hell could be the problem????    Once again, gas key is tight and staked.  

The old bolt looks fine, hell the carrier looks fine too.   I hate to think it's done for, it's a Colt and wasnt cheap.   I got it used and burned at least 5k through it myself.   I dont suppose I can measure it without more tools that I have.   Is there any part that may have become clogged up that needs cleaning out other than the hole through the carrier key to the bolt?   Should I pull the gas key and look for anything under there??

gas tube looks fine, key screws are unmoveable, I already tried with an allen wrench and no way those screws will budge.   Thought about dumping the carrier in a container of gasoline to dissolve anything in other passages?   Cant think of anything else I could do to try to salvage the carrier.  

I figured the gas tube would wear before the key would?   A shot of gunscrubber pours right out the hole at the bottom of the carrier key.   When firing I can literally feel the bolt unlocking so it's probably somewhere between the key and bolt.... or so I guess?   New gas rings and the bolt feels tight in the bore of the carrier

Okay, I literally destroyed the gas key getting it off the carrier.   there was a piece of rock hard carbon partially obstructing the hole.  I pushed it through with a drill bit and it wasnt easy.   Also noticed in the front of the carrier in the area where the gas rings ride what I thought was a dark coating a flashlight showed it was actually heavy carbon deposits.   I let it soak in powder solvent for about 30 minutes to no effect so I got to scraping it all out using various methods.   I can see how it might have all added up to effect the short stroking and the delayed unlocking feel.   I've often disassembled the bolt carrier group and cleaned it up but never really scrubbed the crap out of the carrier itself.   Of course it took years to get this way but hopefully a new gas key will have this back in action.    

Anyone know of a place that'll sell me a key with screws and not screw me on the shipping charges????