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Thread: Power Tube Tip

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  1. #1

    Power Tube Tip

    Hello everyone,

    Recently picked up a minimag and found air gushing down the barrel after firing a few shots.

    Since the gun does not leak immediately upon airing up and only starts to leak after a few shots I am assuming the leak is coming from a bad sear?

    I took the gun apart and replaced the power tube oring, the on/off teflon and urethane oring (on/off orings were shot). What I found however was a cut/gash on the inside of the power tube tip. Could this be causing air to gush down the barrel or would it be strictly internal such as the oring?

    I am going to take my marker out this evening to check and see if the oring swap fixed the leak, and then further assume its the sear or power tube tip if leak is not fixed. What do you guys think?


  2. #2
    Join Date
    Oct 2006
    Houston, TX
    The tip doesn't seal, so it usually doesn't cause much trouble. You use the o-ring on it as a spare for the on/off.

    Make sure your rail bushing is in place. It's a short sleeve in the hole for the rear frame screw, through the rail and frame. If it is missing, the valve can slide back after firing and make it look like your sear or PT o-ring is messed up.

  3. #3
    Hmm first time hearing about the rail brushing.. Ill take a look at it. Is it cloth or metal? I feel I've taken apart my mag many a times and never once ran into this piece. Thanks for the tip, others are greatly appreciated.

  4. #4
    Join Date
    Oct 2006
    Houston, TX

    simple, but necessary.

  5. #5
    Awesome thanks, Ill double check that.

  6. #6
    Join Date
    Jan 2002
    Halifax, N.S., Canada
    How old is your bolt spring? Have you changed it lately? They do wear out and can cause bolt stick issues if worn and weak. If your sear is a bit worn it usually starts off with a leak right away but it is possible that movement of the oring and compression during the first few shots causes it to manifest later. If this is the case, then a shorter powertube spacer will fix your problem.

    Does the gun stop leaking when you hold the trigger in? If it does, then the leak is definitely in the powertube area. If it doesn't stop leaking, then the leak is in the on-off area.
    Except for the Automag in front, its usually the man behind the equipment that counts.

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