- 1). Press the "magazine release" button where the magazine connects with the weapon and slide the magazine out of the weapon.
- 2). Pull the bolt on the side of the weapon back in order to verify that there isn't a round in the chamber.
- 3). Pull out the bolt on the right side of the front of the grip, just before the end of the barrel.
- 4). Pull the grip off of the weapon to expose the entire barrel.
- 5). Unscrew the barrel where it meets the body of the weapon and set the old barrel aside.
- 6). Screw the new barrel in and replace the support grip and replace the bolt.
Source...