M1 Garand - Ported Gas Plug

[Faulkner]

I ordered a "ported gas plug" for an M1 Garand and installed it on one of my rifles. The claim of the device is that it will work with both commercial and M2 Ball ammo without having to make any adjustments. This will allow you to shoot commercial ammunition and eliminate the potential to damage the op rod. The gas plug does not actually port gas, rather it is a tuned port with increased volume that delays the operating rod for several microseconds and lowers the peak gas cylinder pressure by over 30%. By increasing the volume, the peak pressures are reduced without the need to vent the gas.

I've been using Remington 150 grain Core Lokt as my hunting round in my Garand without any issues, but I'm hoping this little modification will give me a bit of relief on the wear on my op rod.

 

[Model25Man]

I've used them for years without an issue. I just bought two more, one for my Win 13, and one for my 'postage stamp' IHC.

 

[LVSteve]

It would be nice if somebody made something similar for the FAL and the FN-49. Yes, I know they have adjustable gas systems, but they run out of adjustment with several types of commercial ammunition. I'm guessing they have very slow and/or dual base powder.

 

[Brian in Oregon]

Faulkner, I ordered and recently received the same exact plug. Goal was to be able to use regular 150 grain hunting loads. It's installed but I have not tested it yet. Supposedly it does not have to be tuned to a specific load like the vented plugs do.

I hope it will reduce the pressures per their specs.

Ported Gas Plug

M1 Garand Ammunition and the Ported Gas Plug

My Garand. If it will work with commercial 150 grain hunting loads, I might take it deer hunting this fall. Bought some five round clips for it.

Pics of the lower pressure gas plug with a GI gas plug. Supposedly a bayonet will not engage the new gas plug. Also, it is not sanctioned for "As Issued" matches. Moot points for hunting.

 

[fordson]

Interesting. I have a vented plug that I picked years ago. Works fine but needs adjusting when I switch loads, i.e., 150 grain to 168 grain bullets. I'll have to check this one out. Thanks for the info.

 

[vonn]

Hope you gentlemen come back with a range report with your observations on how well you think these plugs work. I would like to be able to use my Garand with something besides old surplus ammo myself. Not sure how you will be able to tell the difference in pressure though.

 

[Faulkner]

. . . Supposedly a bayonet will not engage the new gas plug. . .

It will only not work with an M5 bayonet designed in 1953. Has no impact on the M1, M1905, M1942, and M1905E1 bayonets mounted to a M1 rifle.

 

[Brian in Oregon]

Hope you gentlemen come back with a range report with your observations on how well you think these plugs work. I would like to be able to use my Garand with something besides old surplus ammo myself. Not sure how you will be able to tell the difference in pressure though.

There's really no way for the user to know the pressure. I'm trusting the company that made the plug to be accurate with their pressure graphs for the ammo they tested. Did you click on the second link I posted above? It shows the pressure testing method and the graphs. All I can really do for testing is make sure the gun cycles with reduced pressure. I guess the only way to know if there is still excessive pressure is to see if the op rod bends. I also need to get ahold of some M2 ball and see how it cycles with the plug. If any ammo should have a problem with the lower gas pressure it should be the ammo designed specifically for the Garand.

It will only not work with an M5 bayonet designed in 1953. Has no impact on the M1, M1905, M1942, and M1905E1 bayonets mounted to a M1 rifle.

Thanks. I don't have a bayonet yet for mine. Now I know which one not to get.

 

[kfields]

I fell into a bunch of M1 ball in great condition. Will the plug work for that? I realize this particular ammo is corrosive and I will have to clean the rifle after use.
Thanks!
Kim

 

[Brian in Oregon]

I fell into a bunch of M1 ball in great condition. Will the plug work for that? I realize this particular ammo is corrosive and I will have to clean the rifle after use.
Thanks!
Kim

Unknown. Needs to be tested. There are two bar graph charts at the link I posted, each of which has different M2 ball shown. But no M1 ball is shown. The company did say to contact them if you have ammo that they do not show on their charts.

 

[PALADIN85020]

The standard M1 gas cylinder lock screw had a spring-loaded tappet valve (almost exactly like intake/exhaust valves in auto engines) that diverted the operating gas almost entirely by venting the plug when activated by a grenade launcher and used to fire grenades.

The launcher incorporated a stem that depressed the valve through the exterior hole in the lock screw. This prevented extreme gas pressure from damaging the operating rod when a grenade was launched with its special cartridge. Although the M1 could be fired with the launcher in place, it would not auto-reload, and had to be operated manually.

John

 

[OFT II]

John, the earlier plugs didn't have the tappet feature. They can be recognized by having a standard screwdriver slot. The plugs with the tappet valve had what looked like a large phillips screw slot.

 

[2152hq]

Interesting concept,,increasing the volume of the gas cyl sytem to lower the pressure in it.
I have one of the Schuster (sp?) adj plugs in my range toy M1 and like it.
Many hard core M1 fans give an evil eye stare to such things but I like the adj feature to be able to drop the fired brass right next to me no matter the load,,mil-surp or commercial. Saves on my shoulder and the rifle.

 

[PALADIN85020]

John, the earlier plugs didn't have the tappet feature. They can be recognized by having a standard screwdriver slot. The plugs with the tappet valve had what looked like a large phillips screw slot.

Quite correct - thanks for pointing out the difference.

John

 

[Maj Dad]

Wiki has this about M1 & M2 ball:

"...in 1926, the Ordnance Corps developed the .30 M1 Ball cartridge loaded with a new Improved Military Rifle (IMR) 1185 propellant and 174-grain (11.3 g) bullet with a 9° boat tail and an ogive of 7 calibers that had a higher ballistic coefficient of roughly 0.494 (G1 BC),[13][14] that achieved a muzzle velocity of 2,647 ft/s (807 m/s) and muzzle energy of 2,675 ft·lbf (3,627 J).[15] This bullet further reduced air resistance in flight, resulting in less rapid downrange deceleration, less lateral drift caused by crosswinds, and significantly greater supersonic and maximum effective range from machine guns and rifles alike. Its maximum range was approximately 5,500 yd (5,030 m).[16] Additionally, a gilding metal jacket was developed that all but eliminated the metal fouling that plagued the earlier M1906 cartridge.

"Wartime surplus totaled over 2 billion rounds of ammunition. Army regulations called for training use of the oldest ammunition first. As a result, the older .30-06 ammunition was expended for training; stocks of .30 M1 Ball ammunition were allowed to slowly grow until all of the older M1906 ammunition had been fired. By 1936, it was discovered that the maximum range of the .30 M1 Ball ammunition with its boat-tailed spitzer bullets was beyond the safety limitations of many ranges. An emergency order was made to manufacture quantities of ammunition that matched the external ballistics of the earlier M1906 cartridge as soon as possible. A new cartridge was developed in 1938 that was essentially a duplicate of the old M1906 round, but loaded with IMR 4895 propellant and a new flat-based bullet that had a gilding metal jacket and a different lead alloy, and weighed 152 grains (9.8 g) instead of 150 grains (9.7 g). This 1938 pattern cartridge, the Cartridge, Caliber .30, Ball, M2 achieved a muzzle velocity of 2,805 ft/s (855 m/s) and muzzle energy of 2,656 ft·lbf (3,601 J).[15] Its maximum range was approximately 3,450 yd (3,150 m).[16]"