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12/4/2004 11:16:15 AM EDT
Friend has an A! upper, actualy 2 of them marked P  M just below the rear sight windage wheel. Looked on biggerhammer with no luck. The barrel is marked this way  C  MP  B  Any clues on to what kind of upper, and barrel this is. The barrel is a 20 inch marked 5.56.
12/4/2004 11:17:52 AM EDT
[#1]
Don't really know about the "P M" mark, but the "C MP B" barrel is a Colt A1 profile barrel with a chrome chamber and bore, that's what the "B" stands for.

The other sounds like an Olympic barrel, as many are simply stamped 5.56 forward of the FSB.
12/4/2004 11:21:00 AM EDT
[#2]
CM is Colt/Martin Marietta IIRC. CMB is thought of as Colt A2, but yours is an A1?
12/4/2004 11:23:30 AM EDT
[#3]
Its definately A1. I figured the barrel as Colt, but the upper receiver markings P M have me stumped.
12/4/2004 6:39:41 PM EDT
[#4]

Quoted:
CM is Colt/Martin Marietta IIRC. CMB is thought of as Colt A2, but yours is an A1?



"C MB" on the receiver would be a Colt A2 common forging mark, but he stated he has "C MP B" on the barrel.
12/5/2004 10:23:36 PM EDT
[#5]
bump
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