OK, looking to thin my safe out a bit and I am wondering what these old Colt 6551's are going for. The original box is long gone but I do still have the original grip and screw type pivot pin. What is a fair price to list it on Gunbroker?

Part of its value is whether it's a preban model. Any serial number ST038100 and lower will be preban. But the only states that still follow the old 1994 AWB are MA and I think CT. So your potential market is limited.

There's two used ones on GB for $1,300 and $1,800 and one NIB for $2,300. I think the $1,300 one is reasonably priced. My first Colt was an R6551.

http://i1374.photobucket.com/albums/ag409/jsbr1/DSCN0994_zpspjr2dkco.jpghttp://i1374.photobucket.com/albums/ag409/jsbr1/DSCN0995_zps0vyidsyo.jpg

Sorry guys... I still can not figure out how to post pics.

Your pictures are posting fine. Because you have less than 50 posts, they will only show as links until three Team members (who can see them) approve. This is an anti-spam measure implemented by the site admins. I've clicked approve, so they will show for everyone as soon as two more people do the same.

I don't know about prices, but the 6551 seems to be less common than carbines and HBARs and is Colt's closest semi-auto equivalent to a military M16A2. Yours also has a full fence lower and appears to have been drilled for a standard pivot pin detent and spring which are positives, as earlier models had slab side lowers and some were full fence but not drilled. The only downside from people looking for strictly a pre-ban lower (if in fact it is) is the sear block, but that's how Colt made them.

I really like that one.

I do too. I wish I could afford to make an offer, but emergency vet visits and normal holiday spending make that impossible right now.

Thanks for the approval! And yes, it is a pre-ban ser # ST028xxx. I guess I will need to get busy posting so my pics will show up without approval. Thanks for the help!

http://i1374.photobucket.com/albums/ag409/jsbr1/DSCN0996_zps9tnujv2r.jpg

Interesting.  I also have a pre-ban R6551 with box but mine does not have a bayonet lug.  Full fence lower with standard size front pin (going to get it drilled).  It's a really nice version of the A2 I had in boot camp :)

What are the markings on top of the barrel?

Mine says "C MP 5.56 NATO 1/7".  Serial # ST03262X.

Mine says the same

OP can you post a pic of the lower receiver with the upper tilted open? Is there a sear block in the lower?

If you look at OP's pic of the right side you'll see the pin for the sear block just above the selector.