A novel cartridge possesses a fin-stabilized, high velocity projectile attached to a propellant casing, which is selfobturating and expelled from the weapon together with the projectile and separated from the latter on muzzle exit. The projectile is located such that its finned end is within the casing and its front end projects beyond the closed front end of the casing which has a ventable closure at its breech end. Sabot means are removably mounted on the projecting part of the projectile such that they abut against the front end of the casing and are thrown off by aerodynamic forces and centrifugal force of low spin generated by engagement of the casing with the rifling.