Pennsylvania Firearm Owners Association
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  1. #1
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    Default .30 Carbine piston problem

    I can understand that an under-powdered cartridge might send the operating rod only partially backwards, not enough to extract, but once in a while the rifle fires and that's it. No action at all resulting from gases or recoil.

    I have the proper wrench, have removed the piston nut and piston, cleaned the port (which actually seemed clean, as well as the piston cylinder). The piston appeared in nice condition.

    I figure one of two things are happening. One possibility is the piston is able to cock occasionally and "wedge", with no force transferred to the operating rod, although the tolerances seem tight enough to preclude that.

    The other would be the bolt remaining in battery and locking up against any cam action.

    This fired case remaining in chamber happens approximately once in a dozen or so rounds, and not at all at other times, so it is pretty random.

    Actuating the operating rod manually at various (by hand) speeds does not result in any wrong results.

    Not sure what to look for or how to test for it. Help!?
    Legislating to prevent people's acts is fantasy

  2. #2
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    Default Re: .30 Carbine piston problem

    I had the same issue with a bad batch of mil surplus ammo.

    Did you try a different ammo?

  3. #3
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    Default Re: .30 Carbine piston problem

    Quote Originally Posted by Driswalds View Post
    I had the same issue with a bad batch of mil surplus ammo.

    Did you try a different ammo?
    This was my first thought also. I've had some real hit or miss with some old surplus ammo that caused this problem with my carbine. I got some newly manufactured ammo and never had a problem.
    Ron USAF Ret E-8 FFL01/SOT3 NRA Benefactor Member

  4. #4
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    Default Re: .30 Carbine piston problem

    The integral gas system with the barrel is a concern with the M1.
    Keep it clean whenever possible.
    It could save a costly replacement of barrel.
    Think twice, shoot once.

  5. #5
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    Default Re: .30 Carbine piston problem

    These are my own handloads. They are each carefully weighed at 15 grains H110 (max).

    I am not talking about weak cycling. I am talking about bolt remaining unmoved during and after discharge. A lack of piston action, occurring occasionally.

    As it turned out, the piston retaining nut had come loose. I have the wrench. Super-cleaned everything involving the piston system, installed the retaining nut tightly and all is well. Thanks to all for responses.

    Also, bought the bolt tool. Shopping pays bigtime. $50 plus from Amazon, $23 and reasonable shipping from SARCO.
    Legislating to prevent people's acts is fantasy

  6. #6
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    Default Re: .30 Carbine piston problem

    I suppose they starting staking them for a reason .............perhaps keep an eye on it and if it comes loose again maybe consider some loctite as you wouldn't want it to come off.
    It isn't something that needs taken apart often at all .......... and when something works , but then doesn't after you tinker with it ..... always go back and re-check your tinkering

  7. #7
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    Default Re: .30 Carbine piston problem

    I clean after firing, which requires disassembly on an M1 carbine, exposing the nut to visual notice. IMNSHO there are far too many fine threads on that nut for it to come off during the 50-100 rounds I might shoot. It had come loose by maybe a turn and a half, and it let me know it.

    The nut has three rebated sectors provided for staking. Since it is a range rifle used under ideal conditions (including thorough cleanings), staking would preclude the occasional maintenance that it normally would get.

    And, yep, well aware of the concept of self-imposed problems. I think that's where the old saw, "if it works don't fix it" may have derived.
    Legislating to prevent people's acts is fantasy

  8. #8
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    Default Re: .30 Carbine piston problem

    Quote Originally Posted by Bang View Post
    I clean after firing, which requires disassembly on an M1 carbine, exposing the nut to visual notice. IMNSHO there are far too many fine threads on that nut for it to come off during the 50-100 rounds I might shoot. It had come loose by maybe a turn and a half, and it let me know it.

    The nut has three rebated sectors provided for staking. Since it is a range rifle used under ideal conditions (including thorough cleanings), staking would preclude the occasional maintenance that it normally would get.

    And, yep, well aware of the concept of self-imposed problems. I think that's where the old saw, "if it works don't fix it" may have derived.
    I would not stake it either since it is not already ... for no other reason than to preserve the threads ....... hence the loctite comment.

  9. #9
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    Default Re: .30 Carbine piston problem

    What type of LocTite would work in the hot condition the barrel and swaged gas block can reach, while still being removable?
    Legislating to prevent people's acts is fantasy

  10. #10
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    Default Re: .30 Carbine piston problem

    Quote Originally Posted by Bang View Post
    What type of LocTite would work in the hot condition the barrel and swaged gas block can reach, while still being removable?
    I've used blue ...I've used blue for a lot of things even though there was heat involved....... I would not use red even though it's high temp... just see no reason to and
    I should be more clear .... I say "loctite" ........ But I say that generically as I normally have Permatex ...but same difference , just easier for me to find and less $$

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