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8/29/2026 6:47:31 PM EDT
I picked up a new to me barrel and need help dating it.

May be "12" its on the underside near the muzzle
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That's all the markings I can find on the barrel. It's attached to a colt slick side upper with a chromed slick bolt carrier but who knows if all that's been replaced. The 601 charging handle and flash hider are repros

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Here, hold my beer....watch this..
8/29/2026 7:00:34 PM EDT
[#1]
Far more knowledgeable people will chime in but IMO:

-It might be a very early Colt barrel - after the first 14" twist were dropped and before the rifle was in mass production- and so needed to be marked Colt, with the other manufacturers around.
-I see the Colt marks on the receiver.
-But I also see marks where the FSB cross pins were removed.  

   

8/29/2026 8:52:59 PM EDT
[#2]
I’m confused by the laid down “ P”MP or is it VP I’m not sure. I want to think it’s a 602 barrel, that would be cool but I’m not sure.
Here, hold my beer....watch this..
8/29/2026 9:30:55 PM EDT
[Last Edit: ArmaLite_Aficionado][Edited] [#3]
Looks like a weird double-stamped MP 12 to me… 1966 to 1967ish. No chrome in bore or chamber

It is not a 602. 602 would be VP 12 with cast FSB in 1964. In around 1965, M VP 12 followed on 603 and 604, and then the MP 12.

This is a 604 upper.
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