Abstract: The present invention discloses a shot-start projectile apparatus for a w gun tube. The apparatus can be fitted to a projectile as an auxilliary obturator or can be designed to the proper weight and used as the projectile. The apparatus comprises a torque bolt, a rear band, an alignment sleeve, a front band and an alignment nut. The front and rear bands are identical and they are made of metallic or non-metallic material. The remaining components of the apparatus are made of metal. The front and rear bands provide obturation to prevent hot propellant gases from leaking in front of the projectile.