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Rifle upper, M4 Barrel. To Dremel, or not?

Discussion in 'Gunsmithing and Repairs' started by braneu91, Jan 20, 2013.

  1. braneu91

    braneu91 Member

    I have an upper and when I bought it I was told it had M4 extensions , but it doesn't. So I have heard you can still have an rifle upper and an M4 barrel, but it isn't ideal. I do have the skill I believe to cut out the feed ramp extensions. But before I do that I want to know if anyone has run an AR with that combo (Rifle upper, M4 barrel) and if they had any problems.
  2. BBBBill

    BBBBill Well-Known Member

    You will be removing the anodizing when you cut those feed ramps. Assuming that you don't mess up the cuts while free-handing with a Dremel, are you willing to accept the potential wear to the upper from the rounds/case mouths continually hitting the raw aluminum surface? If it won't run well as is, might be better to pull the barrel, sell the upper receiver, and pick up one factory cut with anodizing intact.
  3. carbine85

    carbine85 Well-Known Member

  4. ApacheCoTodd

    ApacheCoTodd Well-Known Member

    Show us a photo. I doubt that you need to - or even should - mess with it but, show us a photo.
  5. backbencher

    backbencher Well-Known Member

    The problem would come if you had an upper w/ extensions, & a bbl that didn't. Your combination should work fine. The Army only added the upper cuts after they had problems w/ the M4 on full-auto - not semi.
  6. braneu91

    braneu91 Member


    Thanks BBBBill I never thought about that. [​IMG] There is an image. It seems fine right now (Not torqued down yet should be today.) I was just wondering if there was any reliability problems related to having a Rifle upper and M4 barrel. Thanks Guys.
  7. 1911 guy

    1911 guy Well-Known Member

    You're fine. The problem can be, as stated by backbencher, with an M4 cut upper reciever and an A2 cut barrel. The nose of the bullet begins traveling through the cut in the reciever and hangs up on the barrel extension. You, however, have the opposite of this and shouldn't have any problems. In fact, I have a 16" rifle set up for HD with the same thing, A2 reciever and M4 barrel. No problems to date.

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