Abstract: A gun for accelerating projectiles in which the travelling chemical charges are ignited by electrothermal energy sources. By one mode there are provided electrothermal energy injectors along the gun barrel which are fired synchronously with the displacement of the projectile within the barrel, each such injector igniting a distinct chemical propellant charge attached to the projectile. Essentially that mode of the gun operates by the travelling charge principle in which the boosting of the thrust on the projectile is brought about by successively ignited propellant charges attached to the projectile itself while the electrothermal energy injectors on the barrel serve for ignition only.By an alternative mode a plasma injector unit is mounted at the rear of the gun coaxially with the barrel and the injected plasma acts via fluid to initiate the chemical propellant and enhances the chemical propellant burning rate to improve the gun performance.