Manufacturing a gun, in a certain sense, is a fairly easy task because a gun essentially requires only three components: the chamber, the barrel, and the firing pin.
The chamber is used to hold and ignite the ammunition. If it's from the muzzle-loading era, the chamber needs to have sufficient airtightness to ensure that the kinetic energy produced during gunpowder combustion does not leak due to poor sealing, affecting the range.
The barrel is used to stabilize the bullet's trajectory, preventing the scatter after the bullet leaves the muzzle from becoming dangerously erratic.
The bullet also requires a firing pin to strike the primer at the base, igniting the propellant, making the firing pin an indispensable presence in a gun.
Simply put, a gun that possesses these three elements can essentially be considered a gun.
