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M1A Adjustable Gas Plug


Product Description

By adjusting the volume of gas in the cylinder it changes the speed of the op-rod and controls the harmonic vibration of the barrel. Even if you only shoot your M1 once in a while make it last a second lifetime.  Our plug softens the blows on your op-rod and wear on the bolt lugs.  Made from Hardened Tool Steel & Parkerized.



READ THIS FIRST: Unload firearm before making any adjustments! You will notice that the setscrew in the Gas Plug may be very tight and will not easily turn  by hand. Once installed in the rifle it will become much easier. The setscrew comes at a factory set position, air will easily blow through it. The rifle WILL NOT FUNCTION at this position. Use it as a starting point, then screw in as necessary until rifle begins to function.

Installation:  Remove existing gas plug, and replace with your new adjustable gas plug. Start with setscrew  at the factory preset position. Turning the screw about ¼ turn at a time, tighten screw, and fire until the rifle functions reliably with your particular load. If the adjusting screws seems to loosen , install the hollow locking setscrew and tighten against the original screw locking it in place.  Locating your Rifle’s sweet spot requires some trial and error. Once rifle is functioning properly, try turning the setscrew 1/8 of a turn at a time and fire a few rounds. Repeat until best group is found. Some shooters like to scribe a small line on the setscrew itself, and use it as a marker for identifying plug position (i.e. 3 o clock).

*Since handloading operations are beyond our control, we disclaim all liability for any damages which may result.

 Need a replacement for the locking set screw? Get one here:Replacement Screw for M1A Gas Plug

Product Videos

How a Schuster Mfg adjustable M1A gas plug is made. (03:35)
This video shows us making one of our adjustable gas plugs for the M1A. We are using a Haas ST10Y turning center. Visit our website at www.schustermfg.com
  • How a Schuster...
    This video shows us making one of our adjustable gas plugs for...

Product Reviews

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  1. Two Garands, Two M1-A's 5 Star Review

    Posted by on 7th Apr 2020

    I bought my first M1-A about 8 years ago. I dreamed about using this rifle with minimal reloads and thoroughly enjoying its function. Addicted to this fun, this time an M1-A "Bush" carbine made in Oct. of 1996 came into the collection. Also 2 Garands for the same reason! No fear of bending the Garand's delicate operating rod. These rifles are now the ultimate for the recreational reloader and the accuracy that you can get out of these rifles while using the adjustable gas plugs will simply amaze you! Not to mention the different gunpowders you can use and different bullet weights. Cast bullets are on the horizon next! Cast bullets with the minimum operation of the action! Sweet!

  2. pointless 1 Star Review

    Posted by on 13th Mar 2018

    I bought this product thinking it would help cycle while suppressed. Which was my fault for not researching it more. But then after researching after purchase it’s a pointless part.

  3. m1a adjustable gas plug 5 Star Review

    Posted by on 29th Mar 2017

    After finding I can shrink group size by half or better, having another m1a in the rack requires another adjustable gas plug. Dollar for dollar you cant beat a Schuster.

  4. Peace of Mind 5 Star Review

    Posted by on 2nd Dec 2016

    Put 100 rounds through the M1A so far. The plug is turning out to be quite reliable. For the price these rifles are going for these days, the plug is an investment in longevity. Would recommend this plug to anyone wanting to save their rifle from unnecessary abuse. BTW, the complimentary candy road kill would make a better refrigerator magnet.

  5. Works Well 5 Star Review

    Posted by on 26th Jul 2016

    I installed this plug on a short barreled (18") M-1A to shot heavy bullets and perhaps use slower powders. It took all of 5 shots to get it dialed in. Function is definitely smoother, ejection not as violent, and the fit and finish on the plug is well done.

0.30 LBS


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