M1 Garand Schuster Adjustable Gas Plug

Discussion in 'Technical Questions & Information' started by LDBennett, Sep 25, 2010.

  1. LDBennett

    LDBennett Well-Known Member

    Dec 20, 2003
    Hesperia, CA
    I have two M1 Garands, a Springfield made in the last month of WWII and a Beretta parts version fitted to a USA made receiver (bought a few years ago from the California sporting goods chain of Big Five). Both shoot well, feed well, extract well, and are tactically accurate. But I use a H335 ball powder middle of the road load. The “experts” say that is wrong and only 4895 powder should be used with M1 Garand loads or the operating rod will bend. I have not seen any signs of that yet but I want to be safe with these guns and not ruin them. So I bought a Schuster Adjustable Gas Plug specifically for the M1 Garand for each gun. Neither gun has been shot that much and the operating rod of the Springfield gun has been replaced with a National Match operating rod because it fit the receiver better (done perhaps ten years ago but shot recently since the change over).

    For the Beretta parts gun the plug fit perfectly but for the “real” Garand made in the USA by Springfield the plug would not fit in the collar that retains the gas cylinder. The rim on the plug that controls the seating of the plug and acts as a stop hits the side of the machined out area of the collar where it should seat. The rim had to be machined by about 5 thousandths to fit. The diameter of the plug body was also a couple of thousandths too big in diameter and the collar needed some material removal with 400 wet and dry sand paper wrapped on a steel rod.

    Now you would think that the USA made gas cylinder collar would fit the USA made Schuster gas plug perfectly and the Beretta part might be a problem but it was just the opposite. I have had the Springfield Garand for 20 years and is a Blue Sky import back from Korea.

    What gives with this???? Everything now fits on the Springfield after the "fitting" but.....

  2. Alpo

    Alpo Well-Known Member

    Feb 3, 2007
    NW Florida
    I can't help with that, but you might think about getting in touch with the makers of your powder. I wrote Accurate, a few years ago, because I did not have any 4895, but had several pounds of several different AA powders. Their resident advice guy gave me three powders and load ranges that will work fine for the Garand.

  3. LDBennett

    LDBennett Well-Known Member

    Dec 20, 2003
    Hesperia, CA

    I reload for a lot of different caliber. In an attempt to minimize the logistics of powder supplies, I limit my choices to powders that meter well through the Dillon powder measure. H335 is the closest I could get to 4895 and the other choices available. The adjustable gas plugs will more than likely do the job to protect the gun. That is not the issue. I have no interest in adding still another powder to my minimize selection of powders.

    The issue is why did a foreign made Beretta part accept the Schuster gas plug and the USA made Springfield part not accept the Schuster gas plug? The Beretta parts are certainly in the minority in available M1 parts. Why would Schuster make the gas plug to Beretta tolerances rather than Springfields?

    In thinking about all of this, I wonder if at some point the gas cylinder retaining collar in the Springfield didn't get changed out before (or even during) my ownership with an clone part made by someone else who claimed it to be MIL-SPEC? The collar worked just fine with the standard gas plugs from both guns. The Schester plug was close and only need a few thousandths taken off the rim and a thousandth or so taken off the collar to get it to fit.

    I guess I am waiting for someone to claim the Schester parts always need fitting (??.

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