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home Forums – The GUN Forum Firearms Rifles AR15 Someone had asked for more pictures of the upper I posted inquiring about the barrel stamp. All I know is I picked it up at a gunshow in Dayton Ohio in 2008 for $72 and It’s a 1-12 twist Colt. Looking for a good lower for it. Not sure if I should try to find a Colt or something else.

  • Someone had asked for more pictures of the upper I posted inquiring about the barrel stamp. All I know is I picked it up at a gunshow in Dayton Ohio in 2008 for $72 and It’s a 1-12 twist Colt. Looking for a good lower for it. Not sure if I should try to find a Colt or something else.

     brian updated 11 months, 2 weeks ago 2 Members · 5 Posts
  • brian

    Member
    June 12, 2021 at 5:05 am

    Someone had asked for more pictures of the upper I posted inquiring about the barrel stamp. All I know is I picked it up at a gunshow in Dayton Ohio in 2008 for $72 and It’s a 1-12 twist Colt. Looking for a good lower for it. Not sure if I should try to find a Colt or something else.

  • bmadoriginal

    Guest
    June 12, 2021 at 5:05 am

    I would stick with a lighter .223 load for that twist rate.

  • frog_prince_2645

    Guest
    June 12, 2021 at 5:05 am

    1-12 twist is the original rate for the M16 using 55 gr bullets.

  • monkewithAnM4

    Guest
    June 12, 2021 at 5:05 am

    $72

    😐

  • yingling247

    Guest
    June 12, 2021 at 5:05 am

    This very likely is an old Colt M16A1 upper receiver. Look at the forge markings by the rear sight windage adjustment drum. CAH, CF or CM markings = Colt. The barrel markings lead to Colt. If it fits a regular lower and doesn’t have a large front pin it’s likely not an SP-1 (civilian version) upper.

    And yes, like others pointed out, 1/12 twist was designed to work best with 55gr ammo.

    As for finding exact year, likely not. A quick google search says since your barrel is stamped C MP B that 1971-1973 era.

    But that thing is damn clean. Looks barely used.$72 for that thing was a steal! Even in 2008. Looks to be in excellent shape. Today you see absolutely thrashed A1 parts kits that lack barrels going for $600+.

    As for what to do with it, slap it on a Brownell’s reproduction A1 lower, get an A1 stock and build an M16A1 clone! At least that’s what I would do. Hit up r/retroAR for some ideas. I would definitely use it if I were in your shoes. A1s are sweet shooting rifles and kind of the OGs of the platform. Very light, nimble, smooth and accurate. I also prefer the simpler rear sight vs the later A2 style sights with rear elevation drums.

    About the only thing I’d maybe consider setting aside on that upper is the hand guards. They were known to be weak back in their day and time has done them no favors. I’d look for a re-pro set for use and keep the originals for show/display.

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