View Full Version : Garand Adjustable Gas Plug

April 12, 2009, 01:49 PM
With the new batch of threads related to the Garand, I thought I should join in and start a new one.

I already have a Winchester '43 Garand and a correct grade HRA coming one of these days from CMP. The Winchester is going to only eat M2 ball but the HRA will probably get one of the adjustable gas plugs. I was hoping you guys that already have them could post some helpful information on your experiences from pros/cons, installation tips and tricks, maintenance issues, problem ammo, etc. Any photos might be of use to us newer Garand guys as well.

moose fat
April 13, 2009, 03:02 AM
It depends on how you want to use the rifle, I think. I bought a Garand last June to moose hunt with. I've been reloading a couple of years and have just begun reloading for my Garand. I started off getting it set for Rem 180 gr. Core-Loct and Bronze Tip. I am in the process of working up loads until the gas system functions with 180 gr. Sierra Pro Hunters.

I have the Schuster Adjustable Gas System/plug because I thought it would offer the most flexiblity.


I havn't tried the McCann Adjustable Gas System. It seems more simple. Find the correct plug for what you want to shoot and leave it alone.


People have been shooting the Garand for a long time. The knowledge base is huge once you start to look. I would recomend getting "The M1 Garand: Owner's Guide" by Scott A. Duff for starters.


Surplus rifles is a great site; a bit of history, tips, more resources.

Love that PING:D


Flatbush Harry
April 13, 2009, 03:08 AM
Go to www.midway.com or www.brownells.com to find adjustable gas plugs. They simply screw into the gas cylinder to replace the original plug.

There are two basic types: the Schuster plug, which is infinitely adjustable, and the McCann plug, which comes with five screw-in ports of various diameters to allow different loads. Both are set in similar fashion: you start with the widest aperture such that the action will not cycle and progressively close the aperture or try a smaller port until the action just cycles reliably with the load you're using. Both protect the operating rod, bolt and gas system from an overpressure due to slow-burning powders, heavier bullets, etc. No special maintenance is required.

Price for each is between $31 and $39. I use the Schuster so I don't have parts to misplace...I also have a Schuster adjustable plug for my M1As.

Good luck and good shooting,


PS-initially try the plugs with M2 ball so you can't possibly hurt your rifle. BTW, I shoot HXP M2 ball through my Springer Correct Grade and get 1-1/2 MOA. It's good, albeit dirty, ammo. I'd use it in any of my M1s and expect good results. I also get great results with my M1As using Lithuanian M80...you don't need match .308 Win to get accuracy (although my Supermatch is a 1/2MOA shooter with Federal Gold Medal Match with 168gr Sierra HPBT bullets).

April 13, 2009, 10:22 AM
Good stuff so far. I plan on getting my new Garand set up to handle modern hunting loads everywhere from 150 to 180 grains. Since I will have two, one will stay "GI".

I was curios as to once you got it installed and adjusted, do you find it need to be readjusted frequently or does it hold?

Yes, I have Scott Duff's books for my M1 and M1a. They are a great resource and I am thankful I paid the money for them.

April 13, 2009, 11:18 PM
I have both the Schuster and McCann. The Schuster has a setscrew and a lock screw. If you're careful with the Allen wrench, you tighten the lock screw down onto the set screw without engaging both screws at the same time.

I never had this one shoot loose, but I couldn't remove the gas cylinder lock screw without removing the set screw/lock screw as these fill the hole!

The McCann design doesn't completely fill the hole, so I've been using it. The orifice insert screw hasn't loosened, but I installed it pretty tight. I take it out once in awhile to verify the orifice isn't plugged up. This gives me some confidence the thing is not only installed, but working correctly. :)

(If you change loads, you have to start over and readjust either one of them. Provided you've settled on a hunting load, you can leave them alone. Or, as one shooter does with the McCann, make up a piece of steel to carry in the stock that has indexed holes for the various orifice inserts, and a laminated card that shows which of your loads uses which insert. Then, if you change between a couple of favorite loads, you save the somewhat tedious adjustment process each time you change.)

April 14, 2009, 02:09 AM
"I was hoping you guys that already have them could post some helpful information on your experiences... tips and tricks, etc. Any photos might be of use to us newer Garand guys as well."

Here's some Really interesting info right from the MI site:


Even More: Their .338 &.458 Magnum Garands: