Abstract: A gun barrel for a hybrid propellant/electrothermal gun has a first barrel portion; a second barrel portion axially separated from the first barrel portion; and an insulator unit forming a third barrel portion. The insulator unit connects the first and second barrel portions to one another and defines a plasma path. There is further provided an arrangement for placing the first barrel portion on a first electric potential and for placing the second barrel portion on a second electric potential. The first and second potentials are different from one another for generating, in the plasma path, an electric arc having an orientation parallel to the barrel axis for heating propellant gases which initially accelerate the projectile.