M-1 Garand Gas Regulator

[Terry G]

I have two CMP M-1 Garands and have always shot GI ammunition nout of them except for Remigton soft tip loaded especially to Garand ballistics. This month's American Rifleman note a gas piston that allowed shooting any .30/06 loads with out danger to the operating rod. I'm going to buy one. Anything I should know about these? Thanks for any help.

 

[Dibbs]

Two things about a Shuster Valve:
1. They require careful adjustment. If you get careless, or rush things, you can still bend your Op-rod.
2. Accordingly, follow instructions carefully, bearing in mind, that if you change ammo type, or bullet weight, you
will have to adjust the valve, again.

OTOH, they could be handy, during an ammo shortage...

 

[Reloadron]

As mentioned one version is called a Schuster Plug and absolutely follow the included directions carefully. The Schuster Plug is so named because they are manufactured by Schuster Mfg. and other companies manufacture similar gas plugs which do the same thing.

Ron

 

[1KPerDay]

There are a couple of different designs. One is “self regulating” and that’s the one I’d personally look into. The Schuster is well regarded but I personally am a set it and forget it kind of guy and I change loads a lot.

 

[Terry G]

This one is called Ported Gas Plug,, garandgear.com $40.00. The article say's you just switch it out and your good to go.

 

[Steve762us]

I just got a $10 solid gas screw off ebaybay, and ground out the face, ala the BM-59 gas screw design. Ten minutes with a Dremel burr, and the volume of gas cylinder
is about doubled.

 

[edwardware]

I have an adjustable Schuster plug in my Garand, and it's worth the $50 for me. I'm still shooting below-max reloads that would be fine without, but it:
-softens the cycle, reducing wear a bit
-let's the brass land in the same zip code
-seems to improve accuracy a bit
-allows me to experiment with the accuracy effects of cycle speed.

There's a shrinking number of people who know how to make or tune an M1 op rod, so I'm going to go a bit gentle on mine!

 

[Dave DeLaurant]

For some graphic content about the Schuster Plug, check out this short video:

 

[Garandimal]

I just got a $10 solid gas screw off ebaybay, and ground out the face, ala the BM-59 gas screw design. Ten minutes with a Dremel burr, and the volume of gas cylinder
is about doubled.

View attachment 927814

And that is essentially what GarandGear's nifty Ported Gas Plug is.

​

Basically a low-compression head.

​

I install one Seasonally, if the Garand goes into the hunting fields, usually with factory Remington 180 gr. Core-Lokts of 168 gr. TSX.




GR

 

[Steve762us]

And that is essentially what GarandGear's nifty Ported Gas Plug is.

​

Basically a low-compression head.

​

I install one Seasonally, if the Garand goes into the hunting fields, usually with factory Remington 180 gr. Core-Lokts of 168 gr. TSX.

Yup. He copied Beretta's design, though I believe I read some discussion over at CMP that
Garand had actually come out with some modified gas management systems, prior to end
of WW2.

Just took a look, here are two. Not going to try digesting em tonite...

https://patents.google.com/patent/US2393627A/en?inventor=John+C+Garand

https://patents.google.com/patent/US2369669A/en?inventor=John+C+Garand&page=1

Second one looks a bit Schuster-ish. Patent apparently expired in 1962, so no harm
there.

 

[HankC]

Ten minutes with a Dremel burr, and the volume of gas is about doubled.

Which burr you use?

 

[Steve762us]

Which burr you use?

Probably spherical. Start with carbide, finish with diamond grit.

 

[Reloadron]

Years ago under the old DCM program, pre CMP I remember shooting some matches where we had several shooters that would swap out gas plugs depending on which line of fire we were on, 200, 300 or 500. Each plug had a tiny drilled hole of a different diameter and they loaded for the different firing lines. I never got that detailed or serious about it. Nice thing about a Schuster Plug or similar is the adjustable feature. While removing some material off a plug will increase gas cylinder volume my experience with removing metal from anywhere on about any gun is it's easy to remove but real hard to put back.

Ron

 

[Steve762us]

While removing some material off a plug will increase gas cylinder volume my experience with removing metal from anywhere on about any gun is it's easy to remove but real hard to put back.

Beretta and the GarandGear guy haven't had any issues, and
mine runs fine.

I doubt you could go deeply enough to cause functional problems,
without breaking through to the screw slots on the outside.

 

[Pat Riot]

Thanks for the education, Gentlemen. I learned something new today.

 

[Reloadron]

Beretta and the GarandGear guy haven't had any issues, and
mine runs fine.

I doubt you could go deeply enough to cause functional problems,
without breaking through to the screw slots on the outside.

Beats me as I never tried it.

On a side note the later Garands used a few Gas Cylinder Lock Screws following the original gas trap design. One was a solid screw the slotted head style designed for removal using the M3 combination tool (or a big screwdriver). Then came a problem as a they began developing a grenade launcher in or around 1940 nothing was adopted till 1944. Anyone familiar with the M14 knows there is a screw which acts as a valve to the gas system allowing the user to turn the gas on or off. When launching a rifle grenade with the M14 the gas is turned off and a blank rifle launching cartridge is used. The M1 does not have that feature and the use of the designated M7 grenade launcher required the use of a valved gas cylinder lock screw. A stud on the grenade launcher held the lock screw open allowing a portion of the gas to escape in turn preventing excessive rearward force from damaging the rear of the receiver (freaking out the op rod). Somewhere around here in a file by pile I have a M7 grenade launcher I was given years ago. I also have a 1940s green flare designed for launch in the M7 but never thought it would be a great idea to try it. On the off chance the thing worked my luck would have the flare come down and start a fire and I end up in jail. The images in post #9 reflect the poppet type design but are left hollow.On the later designs a 1/4" socket fits perfectly to remove or tighten the screw.



I always found I could get my best results loading for the rifle rather than using an adjustable gas plug but to each their own. Just find something that works for you on your gun and run with it.


Ron

 

[rdnktrkr]

I purchased 4 50cal cans of ball ammo for my Garands and I've been loading for them for a while, I feel getting ammo for the gun is easier and better than modifying the gun for different ammo.