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Gas problems? Scrape 'em away!


If carbon is allowed to build and build inside the gas systems of the M249 and M240 machine guns, they fire slower and slower and then not at all.

The key to gas relief for both machine guns is the scraper. Each scraper part is designed to scrape away carbon from different parts of the gas system. And the sooner you use the scraper, the easier the job is. The longer carbons sits, the harder it gets. It eventually becomes like enamel.



* Clean center hole of regulator with POINTED END, turning it clockwise and pushing in until scraper hits bottom


* Clean two grooves on regulator with PROTRUDING TIPS


* Clean inside the front of the gas cylinder with the FLAT SIDE


* Clean the piston grooves by scissoring the SCRAPER around the grooves


* Clean the front hole of the piston with the FLAT SIDE


For the chamber, use the chamber brush and CLP. If your M249 or M240 has trouble extracting, a quick cleaning of the chamber usually fixes the problem.

CLP does a good job of cleaning off carbon, but it also does a good job of collecting carbon. So never use CLP--or any of the other lubes--on the barrel's gas regulator hole, the gas regulator, the gas cylinder, or the op rod's piston end. Clean carbon off those parts with the scraper only--no CLP.

It's OK to use CLP to clean the barrel, the chamber, the rest of the op rod, and the bolt face, but wipe them dry before firing.

Another excellent way to fight carbon in the gas system is to change the barrel on both the M249 and M240 when you're supposed to. For the M240, that means changing barrels every 10 minutes during sustained fire (100 rounds per minute) and every two minutes during rapid fire (200 rounds per minute).

For the M249, during both sustained fire (40 rounds per minute) and rapid fire (100 rounds per minute), change the barrel every 200 rounds.

What you don't want to do with the M240 is change the gas regulator setting from #1. The #2 setting produces much more carbon in the gas system. The #2 setting should be used only in combat emergencies.

If your scraper and elbow grease just won't clean out all the carbon, ask your armorer for help.

Leave M240 set at #1 except in emergencies

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Title Annotation:M249, M240 Machine Guns ...
Publication:PS, the Preventive Maintenance Monthly
Date:Oct 1, 2011
Previous Article:Should both barrels be iD'ed?
Next Article:Tool engraving part 2.

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