The last major component is the lock frame. The lock frame is stationary and contains the trigger and accelerator.
The force of the weapon firing results in the barrel, bolt and barrel extension moving rearward together for about 5/8 inch until the cams on the lock frame force the bolt lock down, unlocking the bolt from the barrel extension, allowing it to continue to the rear on its own.
Depress the plunger and pull the lock frame, barrel extension and barrel out of the casing.
Attach the lock frame to the rear of the barrel extension.
The bolt, barrel extension and lock frame must all have clearance milled into their right sides so they can be assembled into the casing.
Caption: Field strip, step six: Push in the trigger pin through the hole in the casing to release the lock frame.