First, clear the weapon.
Next, turn the rifle over. Grasp the trigger guard at the back. You will see a small notch where the back of the guard goes into the bottom of the rifle. Pull the back of the trigger guard inward, then downward, away from the rifle. The entire trigger group should come out. Lay it aside.
Next, with the rifle still upside down, tap upward on the butt stock until the stock seperates from the rest of the rifle. Lay the stock aside.
Look at the muzzle of the rifle. You will see a LARGE crosstipped screw. Unscrew this, and set the plug aside. Tip the rifle forward, and remove the gas cylinder.
This is as far as you should go for general cleaning. I recommend some Gun Scrubber to spray out the trigger group without disassembly.
For detailed disassembly, consult the NRA guide to assembly/disassembly, and check out Fulton Armory's website. Also, Culver's Shooting Page has a wealth of information on military arms.
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"Be not afraid of any man, no matter what his size;
When trouble rises, call on me and I will equalize."
