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Ported Gas Plug

Availability: In stock


Quick Overview

Our custom made gas plug has a tuned port which increases the starting volume of the gas cylinder causing the peak gas pressures in the gas cylinder to drop by over 30%.
Click images to enlarge

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[CMP Service Bulletin for the M1, 1903,1903A3]

Please note that the Ported gas plug ONLY deals with pressures in the gas cylinder and is not a device intended to lower chamber pressures of the rifle.  Please follow any recommendations set forth by the CMP and verify the headspace on your rifle is also in spec.

Our custom gas plug has been designed to lower peak gas cylinder pressures in your M1 Garand. Our gas plug has a tuned port that delays the operating rod for several microseconds and lowers the peak gas cylinder pressure by over 30%! Unlike a vented gas plug, ours requires no adjustments and is ready to use right away. The gas plug can be installed using a standard 1/4 socket driver!

Our ported gas plug does NOT vent gas like a vented gas plug. The secret is the hollowed out area in the base of the plug which increases the initial volume of the gas cylinder. By increasing the volume, the peak pressures are reduced without the need to vent the gas.

Customer QuestionsQ: Will the ported gas plug work with normal M2 Ball Ammunition? A: Absolutely! The ported gas plug will work with all M2 ball ammunition types made. 

Q: Will the gas plug work with low pressure loads? A: This is a harder question to answer without knowing the load being used. If there is enough gas pressure to cycle the rifle with a normal gas plug, then the ported plug should operate correctly. If the load being tested is marginal, the ported plug may not cycle the rifle reliably.

Q: The product mentions the potential for increased accuracy. Can you explain that? A: Accuracy in it's most basic form is the ability of the rifle to remain unchanged from shot to shot. The M1 has several factors inherent in its design that can cause the rifle to move or shift slightly from shot to shot. Forces acting on the barrel can change between shots. If this occurs then the accuracy potential is degraded. The ported gas plug does two things. The first is to delay motion of the op-rod for a few microseconds. (delays the forces applied to gas piston). This helps keep the system more static until the bullet has left the barrel. The second is to reduce how hard the op-rod is forced rearward. This reduces the natural flexing and bending the operating rod experiences and helps the rifle return to the same state between shots. Recall that accuracy potential is a result of the sum of all the factors acting on the rifle. The gas plug will not make a 5 MOA rifle a 1 MOA rifle.

Q: Will the gas plug work with a gas system that is worn out? A: The gas plug is designed to work with an M1 Rifle that has a gas system that is in spec. That is to say, not worn beyond the normal reject levels. That would be a gas piston with a diameter between 0.5250" and 0.5260" and a gas cylinder that is between 0.5280" and 0.5320". The operating rod spring should also be in spec and not worn excessively and the rifle properly lubricated.

Q: Can I use the ported gas plug on a Tanker or a M1 Garand with a short barrel? A: The ported gas plug is designed to work with a standard length M1 Garand Rifle. A Tanker or short barreled M1 moves the gas port closer to the chamber and results in port pressures that are many times higher then a M1 Garand was ever designed to operate with. The ported design is not suitable for use in this application.

Q: Can I use a bayonet with this gas plug?
A: The ported gas plug is NOT designed to accept a bayonet with a lug that inserts into the gas plug. The lugs on the bayonet are larger in diameter then the 1/4" cutout on the gas plug and will not allow the bayonet to be fully seated.

Q: What causes an Op-Rod to get bent? A: There are three factors that can result in damage to the Op-Rod. The first is high pressure in the gas cylinder. The second is binding of the Op-Rod, and the third is poor lubrication. If any two of the these three conditions is present then damage is possible. If the op-rod is binding then the operating rod will flex and bend when cycling until the bind is overcome. This causes the operating rod to flex and damage is possible. Our ported gas plug reduces the peak pressures in the gas cylinder, which in turn reduces the peak forces acting on the operating rod. Always check your M1 for binding by performing the [Tilt Test].

The effect of the ported gas plug design is shown below.empty chamber         (Click image for full view)
    Custom Made in the USA

[Installation Instructions]


Customer Reviews

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Hot Loads Eject to the Side or Front Now Review by KERRY
After reviewing the excellently presented research offered on this site (I know enough physics to be wary), pontificating and just being skeptical....oh, and reading these reviews...I purchased one.

I was motivated by my stash of HV ammo that I had for my 1917 Eddystone, and was repelled at the prices for Garand-specific ammo.

After a day at the range shooting a hodgepodge of Remington, Winchester and Fiocchi hunting cartridges (up to 3Kfps MV), I am SO pleased.

The casings ejected to my side (two feet) or in front of my station. I also experienced a lesser recoil. I am a skinny kid of 64 years old, so it is good.

I shot well for an old guy at 100yds (6" group of three, five inches above the bulls eye). Then I had to go. Da!M women.

Great product. Arrived early. Cannot say how much this site and product helped me! (Posted on 5/24/2016)
Must have! Review by Chris
I am an engineer, and wondered about the effectiveness of this item. Three things have confirmed it:

1) I had to bump up the charge 0.2 g (of H4895) in my handloads to get the gun to consistently cycle, indicating less pressure on the op rod than with the vintage plug. Now, the bolt cycles back just far enough to consistently catch the next round and ping the clip. Perfect! Felt recoil is more of a push than a pop.

2) Better yet (as I believe someone else has said), before, my brass was beside me, in front of me, and behind me. Now, it is consistently behind me in a 4' radius. This make it much easier to find brass.

3) Gun ('44 SA) was grouping about 2" at 50 yds. Now, I am shooting - no lie - about 3/4" at 50 yds. Why? I think it is because the shot cycle is much more consistent, and I settle back into the next shot more easily.

This is well worth the money. (Posted on 5/5/2016)
No-brainer...just get one Review by Will
I bought a '43 SA Garand a couple years ago with a new criterion barrel and match stock; what a weapon. There is something about the marriage of parkerized steel and dark wood that gets me. She can easily pop melons at 100 yards, and is a great conversation piece to boot. Being an obsessive internet researcher, I learned that advances in powder technology have allowed for a lot more bang to be packed in the substantial 30-06 case than was possible back in WWII. If you are content only shooting surplus ball ammo and you have an infinite, cheap supply, then this plug is a waste of 45 bucks, the USGI one will work fine. If you are like most M1 owners, you want to be able to go to any sporting goods store on a whim and pick up a box of commercial ammo to shoot. I don't know about you guys, but I did not feel comfortable shooting commercial ammo with my GI plug fixed. After running through a stash of M2 ball I bought at a show, I came upon the Garand Gear gas plug as a solution to my ammo woes. Compared with an adjustable plug the Garand Gear Ported Plug seemed too good to be true. How could it allow the weapon to cycle with 150 grain surplus ammo and hot Hornady Superformace loads that have 20% more muzzle energy(3178 vs 2655 lbf)? Then I read the description which explained the science behind the ported plug, and I saw the light. Hats off to Garand Gear for the graphs and data, I do not think I would have bought this product otherwise. Thorough product testing is so valuable I can't even imagine how many operating rods they mangled for our benefit to get those control numbers. What sealed the deal were the positive customer reviews on this site. Shipping was fast and installation is as simple as unscrewing the old plug and screwing the new one in place. I have had the Ported Gas Plug for a little over a year now, and the M1 has happily eaten every type of ammo I have fed it, with no cycling issues concerning enough that I can remember. The menu included a healthy diet of 180g Remington Core-Lokt soft points along with various other loads. The most important factor is that it turns any M1 into a fun, carefree shooter. These guns are pieces of history as well as beautifully crafted machines, and they are meant to be enjoyed. Being able to throw any ammo into the clips and plink has allowed me to enjoy my Garand more thoroughly. For example I was able to shoot a box of hot commercial ammo that my buddy gave me at some pumpkins. Overall, I am extremely grateful that Garand Gear invented this thing because it allows Garand owners to shoot more, period. BUY THIS! (Posted on 12/15/2015)
No More Worries With Commercial Ammo Review by Shane
This product is an absolute must-have for any M1 Garand. I ordered it shortly after I purchased a 1942 Winchester at a local gun shop last December. I've shot over 500 rounds with various bullet weights from various manufacturers and the rifle has functioned flawlessly with no damage to the op-rod. I don't plan on ever using the stock gas plug. (Posted on 10/25/2015)
Works perfectly Review by Bradley
This seems to work as advertised. It has worked flawlessly on my CMP "service" grade rifle. Replaces the original exactly, and you can only tell by very close examination. The only difference is the cross in the screw is slightly more shallow. Fit and finish otherwise is the same as the original screw. I have an original modified (cut down older longer model) WWII bayonet, M1905E1 style, and it fits perfectly with this screw in place. The M1 and earlier bayonets have a ring that goes around the muzzle, and fit over this gas screw perfectly. The later M5 style bayonets have a small knob that fits down into the cross of the gas screw, instead of going around the muzzle. Those might have issues with this gas screw since the cavity made by the cross is more shallow. Others have suggested some light grinding of the knob with a Dremel and re-blacking the grind marks will make them fit, but since I don't have one, I can't confirm.

I can tell this screw reduces the stress on the op-rod and all the parts in the action. My rifle used to throw most of the brass over my shoulder, waaaay behind me, before installing this screw, even with surplus rounds made specifically for the Garand. Now, almost every round comes out relatively gently, and only a few feet straight to my right, or even slightly in front of me. It is also a lot more consistent as to where it throws the brass. This screw makes the action work more gently and consistently.

I'm on here right now ordering another screw for my new CMP "special" grade rifle. The special is an almost new Garand, starting with a receiver in good shape, reparkerized, and mated to a brand new Criterion barrel, a new stock, and finished off with "like new" refinished old parts and new parts. I plan on shooting this one more than my WWII vintage rifle. I may even do things I wouldn't dream of doing with my old one, like replacing the upper hand guard with a rail, for modern optics. (Posted on 8/23/2015)
Valuable addition to your Garand. Review by AFJuvat
Easy installation. Lets you shoot a wider range of ammo in your Garand without beating up your op-rod. (Posted on 7/30/2015)
Great Product for Garand Shooters. "Ported Gas Plug" Review by Frank
This product exceeds its expectations. Now I can use commercial ammo. Lots of hard work & time must have gone into the development of this product and the data doesn't lie.
Thanks from all of the recreational shooters who benefit from this product.

Frank Picini/New Grand owner (Posted on 7/13/2015)
Garand + Commercial Ammo = Shooting Nirvana Review by Kevin
If you have never fired quality modern commercial ammo out of your M1 you do not realize what you are missing. With the Garand Gear ported gas plug I will no longer waste my time on surplus ammo.
Shooting Remington and Federal 150gr, 250 yard hits on steel were a given. Out to 500 yards I struggled a bit with my eyeglass vision but my buddy was easily hitting the targets. Easily outshot a modern .308 shooting new NATO spec ammo.
Modern ammo with modern grease and modern cleaning supplies will make this M1 a regular at the range from now on.
(Posted on 12/10/2014)
The best product and customer service Review by Timothy
First the product
This product makes my m1 into a practical and useful tool or hunting and defense. I was in fear that I could find any m2 ball ammo out there ( I did eventually) but this product solves that problem and If I need ammo I can get it anywhere.
Now the customer service
Only one other person in my life has given me the quality service I have seen here, my own hometown gun shop. Eric has the best service I have ever seen on or near the web keep it up man. (Posted on 9/14/2014)
Review by Tyler Hagen
Just got mine to the range yesterday, shooting a mix of Remington 150gr soft points and American Eagle M2 Ball-spec; it performed flawlessly. For those of you worried about the bayonet, one of the M1 bayonets should work fine for most applications. (Posted on 3/12/2014)

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