Shotgun firing mechanism

How a shotgun works,

The front of the cocking dog protruding from the knuckle of the action bar engages with the knuckle of the fore-end iron.

On pushing the top-lever to the right the arm on the spindle draws the locking bolt rearwards, releasing it from the bites and allowing the barrels to open.

As the gun is opened the cocking dogs rotate with the fore-end knuckle forcing the front leg of the striker (or hammer), upwards to compress the mainspring.

Near full compression the sear engages with the bent holding the striker (hammer) in the cocked position as the gun is closed.