The action spring in an AR-15 semi-automatic rifle helps reduce recoil when the weapon is fired, then supplies the force that drives the bolt carrier and bolt back into battery to chamber a new round of ammunition. The action spring operates inside of the rifle's buffer tube, a thin metallic cylinder secured inside the lower receiver extension that runs into the AR-15's butt stock. In order to give your AR-15 a detailed cleaning, you need to remove both the action spring and buffer tube from the rifle.
Place the AR-15 in a vertical position, with the back of the butt stock resting on a stable work surface. Push down on the slip ring at the base of the handguards, then remove the handguards.
Use a drift pin to press in the take-down pin as far as it will go. The take-down pin is located on the left rear of the receiver, just above the fire selector switch. Swing the back of the upper receiver away from the lower receiver.
Push in the receiver pivot pin and slide it out from left to right. Separate the upper receiver assembly from the lower receiver. Set the upper receiver aside.
Locate the buffer tube retaining pin at the back of the lower receiver. It's at the bottom of the receiver, in front of the opening to the AR-15 receiver extension (the metal tube that extends into the butt stock).
Push back on the buffer tube with your finger, then depress the retaining pin with a drift pin. Slide the buffer tube and action spring out of the receiver extension.
- Brand X Pictures/Brand X Pictures/Getty Images