The knife at the end of a gun is called the bayonet.
Neither. It is called the muzzel
Breach
It is called the "butt stock".
It's called the Muzzle
Threaded
In the cartridge, which is placed at the back end of the barrel, in the chamber.
It's the very back end of a rifle or the bottom of the grip on a pistol.
Back of a boat is called stern and Bow is the front of a boat.
It is the end of the stock as opposed to the end of the barrel end of the gun
abdomen
Firing pin is what strikes the back end of bullet igniting propellant