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Posted: 1/25/2014 5:47:29 PM EDT
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Years ago I bought an upper for my SP1. The tag on the end of the box is...
MODEL AR6521DC It is the upper only and I think it came with 2 10 rd mags. Can anyone give me more info/history. Barrel is marked... C MP 5.56 NATO 1/9 HBAR Receiver is marked... C AF Front sight marked.... F on one side and B (some kind of symbol) 2 It has double heat shields and removable carry handle. Please help. Thank you for your time. Jeff |
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Hi Jeff, welcome to the site.
From your detailed description of your upper it seems like your upper is a model AR6721 AR-15A3 Tactical Carbine HBAR. The model number on your box are a rare export only model similar to the AR6520 A2 Gov't Carbine, which have an A1 type lightweight 16" barrel, standard carbine handguards with single layer heat shields, fixed carry handle A2 type upper receiver. It seems that you might have the box mixed up with a different model upper half. I have two 6721 HBAR carbines same as your upper, except one of my upper receiver have forge marking of stylized D (Diemaco-Colt Canada) and splintered A (Anchor Harvey) and the other with C and keyhole symbol (Cerro). |
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Quoted:
Thank you Alpha-Romeo3. Is this upper worth much or should I go ahead with my plan of using it? They're common and close to the same prices of the other Colt carbine different profiles, lightweight, M4 Gov't profile, and medium-heavy SOCOM. Your upper HBAR version are the least popular among other Colt carbine profiles, but it is the most accurate because of its heavy profile. The HBAR upper probably have a small 0.250" diameter pivot pin (check it first) and I know the SP1 (because I used to have one, it was my first AR long time ago) have large 0.315" dia. pivot pin. So you will need to get a receiver pin adapter, this adapter have a large 0.315" dia. on each ends and a 0.250" dia. at the center of the pin, you should be able to buy it from Brownells, Bravo Company USA, Del-Ton, etc. or you could look at the AR15.com Equipment Exchange (link on top right, orange color button of the webpages), they cost only about from $3 to $8. |
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Thanks again.
Could you tell me the difference in the "new" 6721 that I see on some sites and my "old" 6721. I bought mine around 2002 / 2003. Still need to check the pin size. Also, someone asked for pics. I'll try to figure that out. Thank you very much for your time. Jeff |
The older Colt carbines have the half moon bolt carriers as shown at the bottom left and far right of this picture. Quoted:
Thanks again. Could you tell me the difference in the "new" 6721 that I see on some sites and my "old" 6721. I bought mine around 2002 / 2003. Still need to check the pin size. Also, someone asked for pics. I'll try to figure that out. Thank you very much for your time. Jeff My older 6721 carbine was also made in 2002 and it had that half moon bolt carrier, in 2005 and newer current production they changed the carriers to M16 full auto carriers. The pivot pin on my 2002 carbine is the small mil-spec size 0.250" dia. so yours should be the same as mine. To post a picture here you need to have your pictures hosted at Photobucket, TinyPic, Flickr, etc, and then follow these instructions at the link below. Posting Pictures in Threads - Help content link |
| OP, Specialized Armament has a Colt adapter as well. Its a little more pricey but more refined for application. They are Colt oriented. But truly, don't waste energy if you have a BHC, big hole Colt, KISS and piece together something for your needs. Way to many good deals here to put together a Frankengun. 2cents |
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