I have had some problems with one of my rifles and FTF's.  This afternoon, I had my homebrew bolt carrier and my Colt R6700 bolt carrier out, comparing them.  Naturally, I had a brain fart and am not sure which bolt carrier goes in the Colt.  One is completely open on the bottom, kind of like an upside down "U", when looking at it from the back, the other is a complete round circle on the back, with a small groove at the bottom.  Can someone tell me which one Colt uses??

Thanks.

Bob

Colt: One is completely open on the bottom, kind of like an upside down "U", when looking at it from the back

Non-Colt:the other is a complete round circle on the back, with a small groove at the bottom

OSA is right. It's Colt's little trick for keeping you from installing a lightning link in your gun.

I feel so much safer now.

Quoted: OSA is right. It's Colt's little trick for keeping you from installing a lightning link in your gun. I feel so much safer now.

Come on Ponyboy, it's for the kids!

Thanks for the info, guys.

Bob