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Adjustable Gas Regulator for M1 Garand

JohnnyJohnsoninWI

Hot Rolled
Joined
Dec 9, 2003
Location
North Freedom, WI, USA
Ten or fifteen years ago, I saw a short article in some gun magazine introducing an adjustable gas regulator for the M1 Garand. It was simply a modified regulator with replacable socket head cap screws, each with a different size orifice drilled through it.

Fast forward to last week when I was purusing a new Brownell's catalog. They carry the product described above. They also carry a second product which is advertised as being adjustable without changing screws.

Has any one tried either of these products? What have your experiences been?

Thanks,
John
 
Seems kind of gimicky to me

The distance from Gas port to Muzzle on a Garand is short ...
only very Minor adjustments would be possible.

The design of the rifle kind of limits Bullet weight and powder charges (to prevent bending Op rod or short cycling...)

The original design was primer actuated, but Army insisted on Gas operation. The M14/M1A Cutoff system was designed to reduce the operating rod velocity..

Fine old design, does not need any Pimping.... Shoot approx same bullet weights and velocity as Service Rounds, It IS an old design, just like an Old Car, No Electronics or Power Brakes/Steering.

Just my .02, have been shooting them since I was 16 umm ~30 years now.... :)
 
They make one with a screw adjustment for the mini 14/30.

They make an adjustable gas block for the mini 14/30 that uses a needle valve. You turn a screw to adjust it, I dunno if that's possible for the M1 or not. Anyways, that sounds better than changing bushings. :cheers:
 
The original design was primer actuated, but Army insisted on Gas operation.

Which was because primer actuation was full of problems. Just speculation on my part but I think Garand was trying to develop a semi-auto without infringing on existing patents (mainly Browning's) which is why he screwed around with primer actuation and the almost as bad gas trap.

The McCann plug was developed so heavy bullets with slow powders could be used without wrecking the rifle. In one of my books (I think Kuhnhausen's) it says the gas pressure at the port is supposed to be around 6000 PSI. There are photos on the Net of Garands with the receiver split across the serial numbers from loads that exceeded port pressure specs. With the plugs someone can develop a heavy bullet/slow powder load and then use the jet that vents the most pressure while still allowing the rifle to cycle.

The plugs aren't needed if the loads are made to Army specs. Reloading for the Garand is different from reloading for other rifles. You have to consider max chamber pressure (covered in the reloading manuals) and max port pressure (NOT covered).

I don't personally know anyone who uses this since most High Power shooters use AR15s and M1As. For my Garands I use a load that matches the Army 173 gr match load.

Didn't see the adjustable one on Brownell's site but don't see why it wouldn't work, the FN-FAL has one.

Steve.
 
If you have Brownell's Cat. #60

Check out page 105 for the Schuster M1/M1A Adjustable Gas System and page 106 for the McCann M1 Garand Adjustable System.

I'm aware of the port pressure issue and also that most commercial 30-06 ammunition is loaded with slower burning powders to obtain higher velocity. The slow powders create higher port pressure which can damage the operating rod and possibly other parts of a Garand. AFIK, Federal still loads their 3006 Match ammo with medium burn rate powder.

I've shot a couple OTC matches with my DCM Garand and just for fun I occasionally take it deer hunting. Several years ago I hand-loaded a batch of hunting ammo. My supply has dwindled and I haven't been reloading lately, so I'd like to use factory ammo.

Abarnsley, I respect your opinion on this forum. You surely are more knowledgeable about gunsmithing than I am, I'll grant you that. However, I don't consider taking steps to safely enjoy shooting a fine rifle as Pimping, I consider it prudent.

Take care,
John
 
The Port pressure adjustment ~1 inch from end of Barrel

CAN NOT AFFECT MUCH, DUE TO THE SHORT DWELL TIME OF PRESSURE.

The bullet is out of the bore Microseconds later... Gas bleed time is the amount of time available to bleed thru port before bullet clears muzzle ( a simple bleed non/cutoff port system).. Inertia/weight of Op rod and bolt are not simple items to change.

There will be some adjustment with a gas bleed...... but the rifle is not designed for other than service cartridges, and if you have a single wrong load sneak in, (or wrong bleed orfice in) Bent op rod or worse....

There is no need to shoot heavy bullets or slow powders in the Garand...
Barrel twist is not optimized for heavy bullets anyway.

If you carry a Garand Hunting, must be in good shape... :) I know at 17 or so the thing got heavy... It did lighten up when I saw a deer....

Another reason for not using a Port bleed is... How do you know how fast a powder is in commercial ammo? They might change powder due to cost/availability. As long as Velocity is as stated, they are happy.. Garand might not be...

Best thing is to just reload with 3031 or so, and some decent 165-172 soft point spitzers.

The Mini 14 has a more modern mid barrel gas port, and an adjustment there allows something to actually happen.

Just like aftermarket recoil buffers for many guns (not all)....they cause more problems than they supposedly solve... A lot of guns have come in my shop and left with the add on buffer removed.. The customers did not realize that the malfunctions started exactly the same time they put the buffer in.. The ad said it was good, so it must not be that....

I get a kick out of the add on CHEAP plastic recoil buffers sold for Cetmes and HK rifles, which have a fully engineered, perfectly functioning multicomponent spring buffer system already built in.... Thier sales spiel says you will damage your rifle if you don't have a buffer....

I have a lot of experience with Short Barreled NFA AR15 M16 FAL HK... Shortening distance from gas port to muzzle (Even with FULLY adjustable Gas bleed systems) causes functioning problems. Opening up Port diameter to increase pressure comes at the cost of increased operating rod velocity, and the added wear and tear on extractor and other parts.

The Garand comes with the short distance standard...Changing the port timing/distance from muzzle is the best way to increase flexibility with ammunition. But the Garand is what it is.

I stand by Pimping. It is a 60+ year old design, tried and true, with some flaws, in no need of Modernization..

The Army spent $$$$$ trying to upgrade parts of it (Back when they actually knew how to design something...)

There are numerous simply made, screw on gizmos I could make and sell, but MY NAME will never be associated with a Snake Oil Product....
 
CAN NOT AFFECT MUCH, DUE TO THE SHORT DWELL TIME OF PRESSURE.


That is not correct. Take out the gas plug, load a clip and fire it. The first round doesn't get ejected. Same result every time. If you can reduce the pressure on the end of the op rod by 100%, you can reduce it by less with a smaller hole.

I can't find any details on the Schuster but it almost looks like a standard gas plug with an allen screw to crack open the valve like the stem on the grenade launcher does.

The standard 1 in 10" twist will stabilize up to 210 grains according to the folks at Sierra. When the bullseye is 600 yards or further, heavier is better. If my Garand was my primary High Power rifle I'd be using heavy bullets, a powder to optimize velocity/accuracy and an adjustable gas plug to address the port pressure issue.

Steve.
 
Steve

That is NO PRESSURE, No Dwell....of course it won't work..... Ever use the Grenade attachment???

If the Garand could be so improved by a Bleed screw, the High Power guys using them would rule the roost... Does not seem to be happening :)
Fun Rifle, but it IS Outdated, 8 and 2 round clips.... nice cling when ejecting clip... I shot some Highpower matches with a couple of my M1s and had fun. Came in 2nd (close match, had to go too offhand scores to break tie)

I don't shoot any more matches since the .223 became a High Power round...
Can't see the tiny widely scattered holes in paper at 600 or 1000 on a windy day, when I am pulling pit duty..

Somewhere there is a big fancy Time Pressure Curve, that shows pressure at port. Changing to a Slow powder or heavier/lighter bullet weight drastically changes the pressure at the port in an M1...

I could also Use High speed Cameras and X-RAY technology to show exactly what is going on... But that equipment costs $$$$$$

The Simple thing is, There is a VERY limited amount of time for the gas pressure to act upon the gas piston before the Projectile leaves the muzzle.

Factor in the Inertia of the Bolt Op Rod Assy, and the pressure drop curve of gas pressure in Gas Cylinder after bore is clear.(Remember, once the piston starts moving, the Gas Cylinder area increases as the pressure is already dropping from bore).. Inertia is doing most of the work after bullet is in the Air...

The port is just too far forward for much adjustment...

Yes a simple bleed port in plug will allow some MINOR adjustment...
Will it allow you to shoot 110 or 220 grain bullets and function??? NO
Will it allow you to use ultra Slow or Fast burning powders ?? NO


Stick to what it was designed for, or strip entire forward gas system off and install a M14 Full Cutoff Gas System (Which also has its flaws..) A mid barrel adjustable Bleed system AKA the FAL is another option.

Any gas operated/recoil/blowback firearm is going to be a compromise. It can't shoot every possible bullet weight and function. It can't function with every SAFE possible powder and charge...

You want a ammunition flexible repeater, try an externally powered Minigun or Gatling :)
 
Johnny -

I was curious about the Schuster device so was poking around on the Internet and found a description on Midway's web site. The device seems very similar to one invented by Clint Fowler years ago. Clint has been building match Garands, including one for me, since the 1970s.

Since I know Clint, I called him about it. It is the same one Clint invented years ago which Schuster, whom Clint knows, now makes. It has two allen screws which can be moved to adjust the volume of the gas cylinder. Basically a Garand harmonic balancer. It does work. Clint is a great old guy so give him a call if you want to chat about it or Garand accurizing.

http://m1-m1a-ar15.com

Steve.
 
Question - Gas Piston Mod for a Mini-14

After reading the posts here and the writings of Clint Fowler, I would like to present a question: can the id. bore of the gas piston, used a in a Mini-14, be enlarged? This would create a larger volume for the gas to fill before the slide assm. moves rearward. The idea is to delay slightly to motion of the slide, to allow the bullet to exit the muzzle before the motion of the slide sets up any distortions - vibrations which may cause the muzzle to move from its point of aim. The amount of delay would be small, in milliseconds, as the pressure of the gas is released when the bullet exits the muzzle. This is different than using a smaller gas port bushing, since the bushing is reducing the pressure, but not affecting gas volume. We in the Mini-14 group are trying to improve its accuracy, and have thought that the motion of the slide is one source of vibrations, degrading accuracy. Would like suggestions on how large to increase the bore of the gas piston to achieve this result. And how to actually bore the piston. Your thoughts are welcome.
 
Given the distance between the gas port and the end of the barrel I'm not sure you can accomplish much by working the bore/piston.

Have you either replaced or firelapped the barrel? My understanding is Ruger hammer forges their Mini barrels. I've slugged a number of barrels and the bore on my Mini-30 is the most uneven by far. Firelapped it which improved accuracy significantly. Another thing I've read which supposedly helps is to lap the gas port block to the barrel so it bears evenly. My Mini is on my list of things to tinker with but it's pretty far down the list.

Steve.
 
I like the mini 30 for what it is.

I've got a mini 30, and I don't think it was ever intended to be accurate much over 200 yards. It shoots nice FAST TIGHT groups up to 100 yards, I can put a line of beer bottles on a board @ 30 yards, and bust them all in less seconds than there are beer bottles (one of my favorite things to do). It's just a fun gun to shoot, CHEAP ammo, and doesn't kick bad. I must have got lucky or somebody allready lapped the gas block on mine. It fits on the barrel perfectly. The barrel looks pretty even inside, maybe it's worn smooth. Dunno, I don't understand people that go crazy trying to make a 7.62 x 39 fly like a .308. You stick a scope on there, and it gets hard to settle back down on your target. The only thing I want to do is put a better rear peep sight on mine now that it's got the thumbhole stock on it. :cheers:
 
Mini-14

Our goal is to be able to shoot 1 MOA - 1" groups at 100 yards, 5 shot groupings. I currently can do 2 1/2" groups. Groups remain tight, no "fliers". I have re-worked the gas block assm. and it fits well, torqued it to 30 inch-pounds, installed a smaller gas bushing. And have made a bunch of other mods (17 total). So the rifle does shoot pretty well, but there's always room for improvement! I tried a stronger recoil spring but that actually made the groups larger. Made a barrel shroud/stiffener for the barrel. I agree the sights need to be upgraded, but I'm now using a 3x9 scope, to get it on target. My Mini is a stainless steel Ranch model. Will look at the possibility of firelapping the barrel bore. We all know how s/s cuts. One other thing to try is to have the receiver and barrel cryogenically treated.
 
Could one of these adjustable gas regulators be used to build a Tanker?

-- Brian

Yes, the McCann one could be used to bleed off excess pressure BUT whoever builds the rifle should have put in a gas port sized to properly handle standard ammo.

I'm curious, why do you want a Tanker Garand?

Steve.
 
I'm curious, why do you want a Tanker Garand?

Steve.

Several years ago I purchased a stripped M1 receiver from the CMP and thought it would be fun to do something different with it. I already own half a dozen Garands in mil-spec configuration. Since I'm starting with a stripped receiver I have less reservation about deviating from the original design.

-- Brian
 








 
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