Were gas cylinders on newly mfg. Garands tight without play?

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    Ultimate Member
    Jul 31, 2008
    1,194
    Westminster
    Over the years I've gotten a number of service grade M1 Garands from CMP. Without exception they have had gas cylinders that ranged from a little loose to really loose. Most of them I have tightened Ala Kuhnhausen Shop Manual. I know these rifles may have been disassembled and re-assembled many times during their service life but it is hard to believe the amount of lateral play in some of the gas cylinders would account for that.
    I imagine there were tolerances in the width of gas cyl. splines and barrel grooves and with the mixing of different barrel cylinder combinations the stacking of tolerances could account for this.
    I recently purchased 2 CMP Special grades in 308 that were several years old from GB. One was unfired and the other was fired very little. They both have newly mfg. Criterion barrels and the gas cylinders are tight as a tick on the barrels. I have to say they may be my most accurate Garands.
    Anyway I got to wondering about the fit of the gas cylinders to barrels on newly mfg. Garands back in the day. I have never held and unissued or never fired Garand from the WW II era. Does anyone have an answer to my title question?
     

    Doco Overboard

    Ultimate Member
    FM 23-5 describes as part of the pictorial using about a 10" wooden block as a mallet to "tapping the gas cylinder off lightly" at the bayonet stud. I'm sure others will advise driving the GC on tightly to eliminate gas leakage at the barrel splines and to keep the front site constant which is good for accuracy.
     

    Doco Overboard

    Ultimate Member
    Just measured an unused criterion barrel against a very well used SA 44. What I found was the CR spline slot was at first or near .122 and SA barrel had spline slots .125 wide. The criterion slots were .035 deep vs. .032 on the SA. The length of the slots were different by .010 but the pad width was the same at .600 on both barrels. The diameter of he muzzle was .515 on the cr and .510 on the SA. The diameter of the criterion barrel was .684 at the rear of the pads and the SA .685. The gas cylinder in hand measured .122 and wouldn't even come close to starting. At first I thought that the barrel taper meant that the rear ring of the GC would start to bind faster on the criterion but that's not the case they measure the same diameter at the point where the GC would be positioned and the splines begin contact before the rear ring of the GC reaches the larger barrel diameter where it seats. I went back and remeasured the width of the splines again and where I thought they were both the same I found I measured wrong and the criterion is closer to .120! The gas cylinder I have in hand measures .121 spline width and wont even begin to start so its going to need a couple good wacks to create its own interference fit. With the steel of the gas cylinder harder than the soft barrel steel I would say it would pay to support the GC well when removing the plug to prevent the splines from becoming increased in width. I would also say that a newly issued rifle would have needed some real good whacks at the factory on initial fitting. With the GC removed on a fresh barrel I bet you can see by eye where the slots have been interference fit unless the GC has been driven clean into the front of the handgaurd allowing the two to touch. That tight without being driven so far back should also keep the rear ring from being sloppy and contacting the barrel too. I also learned that it may not be a good idea to heft the weight of the rifle by grasping the Gas cylinder as well and could explain loose fit on a lot of rifles.
     

    Orlando

    Active Member
    Original manufactured Garands the gas cylinders fit very tight, there was a machine that actually pressed fit them on
    I have built many Garands with unissued gas cylinders and barrels and they all fit very tight and had to be driven on. Several were so tight I split the hardwood block when driving them on
     

    Augie

    Ultimate Member
    Sep 30, 2007
    4,504
    Central MD
    Original manufactured Garands the gas cylinders fit very tight, there was a machine that actually pressed fit them on
    I have built many Garands with unissued gas cylinders and barrels and they all fit very tight and had to be driven on. Several were so tight I split the hardwood block when driving them on

    Yup, I have 2 Correct Grades which are basically brand new 50's Garands and I had to hammer off the gas cylinders, they are designed to be tight.
     

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