Well, my 601/603 build is complete.  Everything is Colt (including lower parts kit) except for the stripped NDS 601 lower, AND THE DAMN BOLT CARRIER GROUP!  I got it from a buddy "pay me later" for the M4 upper.  It is a brand new, unfired M16A1 Bolt carrier with shot peened MPI bolt.  "So what's wrong, you ask?" It's NOT Colt.  I was going to go up this week and shoot both uppers (using the new, unfired BCG).  But I really need to find a Colt.  He doesn't want it back, just paid later.  Argh RBRD, I hate you!

IT NEVER ENDS!

It really doesn't. I have a Tool Craft chrome carrier in my 607. "Oh it'll be fine, it looks close enough." I said... So why am I now looking for a Chrome XM16 carrier?

Haha! I understand.  Actually, there is an original XM16E1 BCG on the EE, only $399!

Anyway, I have to just use the new carrier for now, until I raise the $$$ to get one for $135 from that surplus guy in the other thread.  That will be awhile, though.  Hopefully he still has them.  I'll then use this carrier dedicated to the M4 upper, which I am sure will eventually grow another cheap A2 lower..... SAVE ME!