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new chiappa M4-22 upper on new plum crazy lower will not fire

Discussion in 'Rifle Country' started by olddog-newtrick, Jun 4, 2011.

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  1. olddog-newtrick

    olddog-newtrick Member

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    May 31, 2011
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    Location:
    West Kentucky
    pinned it together, round chambed act's like firing pin not hitting, no marks on the round, pulled bcg out wiped off & oiled, put paint on firing pin, put back together went click. pulled apart no paint on hammer. any thoughts thanks
     
  2. Stack

    Stack Member

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    Mar 26, 2011
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    I had a similar problem when I assembled a Plumb Crazy lower matched to a DSA upper. I pulled the bolt apart and found the firing pin was floating in some very heavy oil. Kind of between grease and gun oil in consistency. I sprayed the bolt and carrier down with some aerosol CLP and re-assembled the BCG making sure the firing pin moved easily and voila!
    Hope this helps ya.
     
  3. runninmt

    runninmt Member

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    Location:
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    Olddog-newtrick, did you ever find out what the problem was? I have the exact same problem with the same set up. Seems like the hammer isn't even hitting the firing pin. I removed the bolt carrier group from the upper to take a closer look. Seems I can't even make the firing pin protrude from the front of the bolt while pushing it forward with my index finger. Maybe broken firing pin?
     
  4. 7.62 Nato

    7.62 Nato Member

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    Could it possibly require a different hammer like some of the 9mm uppers? Does the lower have a standard/milspec hammer?
     
  5. wally

    wally Member

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    It the Chiappa upper is anything like my 1911-22, there is your problem.
     
  6. Rail Driver

    Rail Driver Member

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    The plum crazy lowers have a hammer that is wider than a standard hammer. Swap out the LPK with a standard LPK and it will fire. You can also file down the sides of the plastic hammer so it fits in the slot and hits the firing pin. This is a well known and common issue. Also PCF sells a replacement hammer that will work with the dedicated .22LR uppers.
     
  7. 68wj

    68wj Member

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    That's the word.

    Narrow hammer available here: http://www.joeboboutfitters.com/PlumCrazy_Blow_Back_Hammer_PC_BlowBack_p/pc-blowback.htm
     
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