After clearing the shotgun of ammo, remove the barrel, and forearm. Then the barrel seal ring (rubber), the piston, and piston seal taking note of their order. Drive out the two pins holding the trigger group in making sure the hammer is cocked first. Then pull straight out the operating handle on the bolt.
Grasp the action bar forward of the receiver, and while pulling forward on it, reach in and depress the shell stop sliding the entire bolt assembly out, action bar and all. Look how it's mounted on the action bar. It goes back in the same way.
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