Fourth installment; Prepping the Gas-Cylinder

[Dave Waits]

Prepping the gas-cylinder on a Match-grade M1 Garand involves alot more than thought at first Blush. First thing, of course, is too make sure you have a good, servicable Gas-Cylinder. Before you take any measurements it needs a thorough cleaning. I use a bucket with a quart of ATF and about three-ounces of Kerosene added, drop the gas-cylinder in and let it soak for a day.
Then,I take a brass scrubbrush and scrub down the outside, next a 20ga.shotgun brush on a rod to scrub out the tube. Finally, a 90-degree angled dental pick to scrap out the port. Be sure you use the brass scrub brush to thoroughly clean out the threads. Now, blow all the ATF/Kero off with brake cleaner and let it sit for a day.

Okay, the first thing you have to do is check the Chamber-Diameter. This is the area right behind the threads. I use a Gas-Cylinder Chamber-gauge but, they cost about $125.00. Luckily, the Belt on a Remington 7mm Magnum case is .531 and you can use this to check with. It should either not enter the area behind the threads or just enter. If it does, hold the cylinder up to the light and look from the back of the tube. There should be no light visible around the belt. If there is, the gas-cylinder is unservicable I'll assume it passed the test so, we'll go on.

First item is to polish the frontsight base. You'll need a fine Arkansas stone for this. You want a smooth, flat surface, no notches at the edges. Take your time and be sure to hold the stone flat and square as you polish the sightbase flat with it. You can also use a piece of fine Crocus-cloth on a flat metal surface and push the sightbase flat on it and polish in a circular motion. but, it takes alot longer.

Next, we need to open up the rear ring the barrel slides through. I ream it out to ten or fifteen thousandths over original diameter. I use a Dremel with a fine sanding drum. Adjust it to just fit inside and run it in and out. Next, tighten the screw about 1/8th turn and do it again. Then tighten one more time and run it in and out. That should clearence the ring. The idea is for the ring NOT to contact the barrel.

Okay, now comes the hard part, squaring the rear of the Gas-Cylinder. This really should be done by a machinist on an end-mill. You want to take about five-thousandths off, just enough to square it, the entire area above the tab. This is so you gaurantee the back of the Gas-Cylinder doesn't abut the front handguard ferrule. If you take your time this can be accomplished with a #2 swiss-file, checking every so often with a machinists' square.

Finally, if you look at the bottom of the Gas-Cylinder, you'll see a square tab sticking out aft of the Stacking swivel boss. What you are going to do here is break both corners of this tab so they don't contact the front handguard. You want to start at each corner and bisect it,marking the tab 1/8th inch in towards the center, with the line going all the way to the back of the tab where it meets the Gas-Cylinder. File everything from the line out to the corner off. The Tab will look like a broken arrow-head afterwards.
Done.