This is an old Colt SP-1 upper (marked CM), large front pivot pin, no forward assist. The barrel is an Oly medium weight 20" (marked 5.56) with flash hider and bayonet lug, triangle hand guards. I'm not sure about the bolt and carrier, I don't see any letters or other markings on the carrier. Also includes charging handle. Is in good, not great condition overall. I have pics if you're interested (how do you post pics, anyway?). I'm asking $250 shipped.
Thanks for looking, thanks AR15.com.