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CMMG Parts kit?

Discussion in 'Black Rifle Forum' started by collim1, Feb 5, 2013.

  1. collim1

    collim1 Shower Time!

    Mar 14, 2005
    I am helping a friend put together an AR. The bolt stop catch roll pin hammered flat on the end instead of hammering in. It essentially made a rivet by flattening the end we hammered with the punch instead of driving in. It was almost as if the roll pin was really soft metal.

    Its not gonna do, I am going to have to drive it out and put a new one in. I was wondering if this is something CMMG has a problem with? Its never happened to me before, and it happened from the start, I know it didn't happen because the bolt stop wasn't lined up correctly. If it is I'll tell him to order one from another manufacturer. If not I'll tell him to call CMMG and get a replacement sent.

    Other than that the installation went quick and easy. That pin not being flush is just going to bother me, so I have to fix it.
  2. Mayhem like Me

    Mayhem like Me Semper Paratus

    Mar 13, 2001
    Not a chance
    Punch out and dress it down with a file or dremel.

    I always use taped parallel jaw pliers or a vise grips to install that pin.

    Did you use a roll pin punch with the dimple end. If not its common for them to peen.
    Last edited: Feb 5, 2013

  3. dkf


    Aug 6, 2010
    Could be bad or no heat treat done on the pin.
  4. collim1

    collim1 Shower Time!

    Mar 14, 2005
    No I did not. I'll try driving it out and straightening that end.
  5. Cole125

    Cole125 Silver Member

    Apr 5, 2008
    Far West, USA
    I have a CMMG lpk in one of my builds with no issues, as good parts as any. Keep in mind you need to use a correct size roll pin punch for best results driving in pins.

    Brownells sells a kit for building AR lowers.

    Get the correct punch, another roll pin, and try again.
    Last edited: Feb 5, 2013
  6. Be careful when you drive the pin back out. If your punch is too big in diameter, or if you drive it out with a crooked punch it might enlarge the roll pin holes, or even break off one of those roll pin ears on the receiver. Always make sure that the punch is parallel with the receiver when you drive out that roll pin.

    There is a special tool/roll pin punch which allows you to drive out that roll pin from the other side without damaging those ears/receiver.

    Tool link:

    Good luck!
    Last edited: Feb 5, 2013
  7. collim1

    collim1 Shower Time!

    Mar 14, 2005
    Thanks for the help guys. I am going to get a proper punch and replace the roll pin with a fresh one.

    We finished the assembly last night and all went well except for that one pin. My buddy really picked a bad time to start a build, it took him 2 months to acquire the parts.

    He bought the lower a couple of days before Sandy Hook and we all know how it went after that. The complete upper he ordered in December just shipped on Monday.