Ah, just by chance I hauled one of my Garands out of the safe Monday for a Memorial Day excursion to the range. I'd forgotten what a pleasure it is to shoot a Garand over the NM course of fire.
Anyway, I've never once cleaned a gas cylinder on any of my Garands. Well, I did, once, after I found out that some foreign surplus ammo I'd been shooting was corrosive.
The USMC manual discourages cleaning the gas cylinder, their reasoning being that the hot gas burns off the carbon, and since the fit of the piston in the cylinder is not all that tight, any particulate matter either falls out the vent hole or escapes around the piston. If carbon does accumulate from dirty ammo, the piston acts as a scraper as it goes forward. The manual notes that the gas cylinder screw can be taken out if you want to dump out this carbon, but they strongly discourage taking the cylinder off the barrel unless the rifle is in the armorer's shop for general refit. The reason for this is so you don't "wallow out" the splines on the cylinder and barrel, or otherwise mess up the timing of the gas port.
As others have noted, don't put oil or grease in the cylinder, it will just gum it up.
If you think the op rod has become worn, send it to Clint McKee at Fulton Armory - he can either sell you a new one, or have the old one "capped" to correct tolerance.
Regards,
Ken Strayhorn
Hillsborough NC
