That is the rear end of the barrel where the shell is inserted.
Near the breech.
From the breech.
From the breech
Where the shell is loaded.
Autos and pumps, on the receiver. Over/Unders are undr the breech locking lever
In front of the butt stock .
Less than $100.
Serial no. C8172
The Darne sliding breech shotgun comes to mind.
The wooden piece under the barrel of a breech-loaded shotgun is called the forend or forearm. It serves to protect the shooter's hand from the heat of the barrel during firing and provides a secure grip for handling the shotgun. The forend can come in various shapes and styles, often reflecting the design and aesthetics of the shotgun.
I'll take it for free :)
Try e-gunparts.com