shuriken gun

A gas powered shuriken gun with a disc magazine and quick release gas housing. Would fire approx same rate as a pump action shotgun. Gas would enter into a spring loaded piston chamber driving the piston back with a nipple inside a rail engaging the shuriken. Upon release the piston springs back flinging the shuriken out. The fins on the side of the barrel rail direct the escaping gas such that it spins the shuriken. This is my first project so bound to be some things wrong, so making it free so