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Posted: 9/13/2004 7:32:24 PM EDT
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Colt hasn't marked anything regarding chrome on their barrels in at least 25 years. That was originally done in the mid/late 60s, to indicate that replacement barrels were chrome-lined, as the original mid-60s barrels were not chromed. By the mid 70s, Colt and all military manufacturers had gone to a standard format: C MP 5.56 NATO 1/7 C = Colt or whoever the manufacturer is. M = Magnetic Particle Inspected P = Proof Load Tested 5.56 NATO = Chamber Dimensions (this is the marking for the military chamber dimensions) 1/7 = Barrel Twist Rate A Bushmaster barrel, let's say a 16" HBAR 1:9, will be marked: B MP 5.56 NATO 1/9 HBAR Note that the "HBAR" isn't any kind of military requirement; Colt put that on their civilian barrels in the 80s when the HBAR was first released, and marking them that way is kind of a tradition now. A Bushmaster DCM barrel will be marked: B MP .223 REM 1/8 These are match barrels that use the SAAMI-spec .223 match chamber, and they have a 1:8 twist rate. -Troy |
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