Press the release button located where the magazine meets the underside of the rifle and simultaneously slide the magazine out of the rifle.
Pull the chamber bolt on the side of the chamber back in order to expose the chamber and verify the gun isn't loaded.
Press the plunger on top of the hammer down and simultaneously pull the barrel cover off the weapon.
Lift the spring-loaded retracting mechanism out of the weapon.
Use your Phillips screwdriver to remove the two screws above the trigger guard to free the trigger assembly.
Lift the trigger assembly out of the rifle and fit a new one in its place.
Replace the screws on the top of the trigger guard.
Replace the spring-loaded mechanism and chamber guard.