The AR-15 is a gas operated, air-cooled semi-automatic assault rifle. This weapon is among the same family of AR style weapons -- such as the M4 and M16A2 rifles -- currently used by the U.S. military. When a bullet is fired, the expanding powder gas is redistributed via a gas tube to chamber which fires the next round; this results in a high rate of fire and cycling. If a gas tube becomes bent or damaged it needs replacement. You can remove the gas tube using gunsmith tools.
Unload the weapon completely. Visually inspect the weapon to ensure that no live ammo is present.
Pull the charging handle to the rear, then push it back forward.
Push the front and rear take-down pins using a cleaning rod or a pointed tool. The pin will not come out all the way because of a retainer. Pull the rifle apart, separating the barrel and action from the stock and grip.
Pull the charging handle to the rear to remove the bolt-carrier group.
Pull back on the hand-guard-release ring then pry off the upper and lower hand guards. Note the gas tube running parallel above the barrel, from the front sight to the barrel lug.
Place the barrel and action into a padded gun vise. Ensure that the gas tube is accessible.
Knock out the gas tube's retainer-pin using a punch and hammer. The retainer pin is located on side of the front sight, in line with the gas tube.
Slightly wiggle and pull back on the gas tube. If the gas tube is stubborn, do not use force it; a bend or crimp in the tube will render it useless. Apply a metal lubricant to the gas tube and slowly rotate it back and forth until it becomes loose. Pull it out of the sight block.
- Never attempt maintenance on a loaded firearm.
- Never point the AR-15 at anything that you do not intend to shoot or kill.
- Don't grab the gas tube with pliers as this will damage the gas tube.
- Consider buying an AR15 gas tube removal-tool if your gas tube seems frozen in place. The tool looks somewhat like a screwdriver and will not damage the tube.
- Photodisc/Photodisc/Getty Images