What's different about this gas cylinder?

[burpgun]

I received this rifle directly from the CMP. S.A. #1451994 BBL. marked S.A. 9-42 Do any of you have a similar gas cylinder? It's a great shooter so no problems there.

Information

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[M1 Rifleman]

The diagonal cut does not affect shooting the M1. There are several books (ie Duff, Harrison, etc) which detail the diagonal cut on the gas cylinder. Your rifle's serial number indicates that the diagonal cut was used at the time your rifle was created (c. 1943).

This was done as hundreds of Gas Cylinders were discovered to be "out of spec" and were not tight on the barrel. The GC allowed gas to leak out and thus affect the semi-auto nature of the M1. The GCs were segregated, a diagonal cut was made to tighten the GC on the barrel and reinspected. Due to the diagonal cut: thousands of dollars, production time, and valuable materials were, thus, saved.

[burpgun]

Thanks for that. I see through a search that this has been discussed previously. My apologies.

[BruceV]

What you have is a Gorilla Grip Gas Cylinder. Many soldier took great pride in their experience in boot camp, especially the scores they fired in qualification. Sadly they found the realities of combat were not conducive to target accuracy. Targets did not stand still. Ranges were not a known distance. Bullets were going in all directions. And especially disconcerting was the discovery by these now frustrated front line combat soldiers that their issue weapon was not always capable of sterling rifle range accuracy. Extensive field level testing determined that a lot of the problem lay with gas cylinders that were loose on the barrels. This led to a wobbly front sight. With no access to aluminum cans and no availability of drill bits and hammers to "adjust" the gas cylinder splines on their rifle barrels, complaints about the loose gas cylinders became louder and louder. In response to customer complaints, SA developed this modification to standard issue gas cylinders so as to allow front line combat soldier a means by which to wring the best possible target accuracy out of their combat rifle. (The preceding has been brought to you by to much fresh ground coffee, some time spent reading this forum, a wandering mind and tongue firmly planted in cheek). Sincerely. BruceV.

[dryheat]

I am looking for one of those. I have a barrel that is very worn at the pads and losing enough pressure that it won't cycle. I thought a cut cylinder might tighten it up some. I don't want to cut a good cylinder to try it.

[islandhopper]

I'm pretty sure it was the barrels that were out of spec and not the cylinders. There were two different kinds of "saw-cut" cylinders. The first being the straight across, which left a smaller section of the dovetail at the front end, which made that section prone to breaking off. The next version was the diagonal cut, which allowed for structural integrity of the dovetail. I'm also pretty sure that the straight across cut cylinders were to be replaced during rebuilds but the diagonal cut cylinders were okay to use in service. They both work fine, again, it was just that the straight cut versions were more prone to breaking the dovetail if the front sight was really cranked down. It is also my understanding that some of the straight across cut cylinders were field modified by having the cut welded shut.

[burpgun]

I can say from experience that the "Gorilla Grip" gas cylinder can be tightened to the barrel such that it will not move at all. This may partially explain why this rifle can shoot consistant tight groups that are more in line with a N.M. prepared M1!

[BruceV]

Dear Dryheat,

Do not get in a sweat. You can most likely purchase an official "Three G" gas cylinder, contact "John R." He is a friendly gentleman north of the border who has, from time to time, sold beautiful USGI gas cylinders to many happy customers south of the border. Do a search for his name. He will likely be able to help you. Sincerely. BruceV.

[islandhopper]

Just remember that if you ever remove the cylinder, you need to loosen/remove the front sight as well, since that is what is pinching the dovetail together and therefore gripping it tightly to the barrel. I would keep it just as is though if it were my rifle. It looks nice. Is it a narrow base cylinder?

[albud3]

I have a gas cylinder that's cut the same way: rifle shoots great, therefore I'm not thinking about replacing it any time soon.
Just shoot and enjoy!