Abstract: A gun barrel weapon for firing a projectile by means of a liquid propellant medium. The weapon includes a coaxial first member which defines a propellant medium combustion chamber. This first member also functions as a breech or breech block. A second member defining a projectile chamber is disposed between the first member and the gun barrel. The combustion chamber is adapted to hold a liquid propellant medium and includes a neck portion of narrowed cross-section which throttingly communicates with the projectile chamber. The first member also includes a plurality of through-bores which form conduits between the projectile chambers and the combustion chamber.