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Posted: 8/18/2006 5:35:39 PM EDT
| My dad give me a stripped colt lower, on the left side of mag. well it is marked, match target competition - hbar - cal. 223 ser. CCHO20XXX. Above the trigger it's marked colt's mfg. co. inc. hartford. conn. - u.s.a. -. It looks a bit different from my bushmaster lower, but the pivot pin's of both are .250'' dim. Will a Bushy,RR,orCMMG upper mate to the colt lower. If it will i just started my first build. Any help would be appreciated |
Short version since I don't want to dig through information to see if the lower is mil spec or not. Look at the ejection side of front pivot pinhole. If there is a small bump/hole for a detent pin to capture the front take down pin, then it will accept standard Mil spec upper. Note: even if the receiver uses the colt screw type take-down pin, there are pin adapters that will allow you to use a standard mil-spec upper on the receiver. Next look at the back shelf of the receiver where the upper back lug will mate with the lower. If you have a protruding block sticking up, then you will need to get a Colt C cut carrier (read the sear block will not work with a standard SP-1 type carrier). The last is the FCG holes in the receiver. Colt offered two different FCG hole sizes. The old hole size is .170, and then they went to the mil spec of .155 later on. If the receiver is milled/drilled with hole sizes @ .170, they you will need the Colt sized FCG, if not, then a standard mil-spec size FCG/pins will work with the receiver. |
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thanks for you're help Dano the rec. has a colt screw type pivot pin rec. is flat except were the stock screw's in the back holes for the trigger & hammer are .170" hole for bolt rel. is about .150" hole for mag. rel. is about .200" If i can do something with this rec. i'm going to build a 16" for my son. thank's again Dano |
Great find and the mark up from dealer price to retail price isn't even enough to hunt for a dealer to buy it for you instead of direct yourself. |
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The first Colt flat top upper I ordered was a stripped flat top upper. No M4 feedramps. I want to use a Colt 10.5 barrel from SAW and it has the M4 feedramps. I exchanged the Colt upper for the M4 type and Brownells came through. I received a NEW M4 upper with FA and EP assemblies installed. PLUS perfect service from Brownells. If requested I can do part numbers Sunday. |
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