Machine Gun Maintenance: Oil Attraction

Where to lubricate and not lubricate on machine guns and their gas systems.

The Concept

A M240L gas regulator with caked on carbon

The concept is quite simple. Don’t put lubricant on anything that comes into direct contact with the gas system in a machine gun.

The Machine Gun Gas System

A lot of these systems come with a gas system that has three simple parts you need to watch for problems. The gas regulator, gas cylinder, and piston. These parts are inherently important to keep free and clear of caked on carbon to allow proper gas pressure.

Parts to Keep Lubricant Off

The manual states NOT to put CLP (Cleaner, Lubricant, Preservative) on gas regulator, barrel gas port, piston, interior of gas cylinder, and bolt face.

If you do need to use CLP, let it soak for a bit before removing the carbon and be sure to use a dry cleaner after to dry the rest of the CLP off. I use dry cleaning solvent.

A piston with caked on carbon on the inside

Next Maintenance Article.. how to remove the carbon (and rust).

Scraping at carbon with the Multitasker Tools Series 3x

Disclaimer: I am referencing Mil approved CLP to all of these statements. It is known to pull up carbon as it is a CLEANER, lubricant, and preservative. If you are using a different lubricant it may work, but differently and with unknown long term effects. However if you are using a lube in relation to Mil CLP it may do these same things.

[Editor’s Note: This is a prudent thing to do for any gas piston system by the way. Machine guns just see a lot more rounds.]

Anna Martinez
Anna is a Federal Weapons Gunsmith with 8 years of previous experience within the US Army Ordnance Corps (91F). She has taken multiple armorer and weapons proficiency classes to include FN, Knights Armament, and Small Arms Weapons Expert course. She also writes for American Gunsmith, AR Build Junkie, and is active in Precision Rifle sports around the nation.