used additionally the exterior surface of the cartridge case 41 rests against or is adjacent to the chamber insert 17 thus the cartridge case 41 is adjacent to the chamber fig6 b depicts a side sectional view of a second embodiment of both a gun barrel 10 and the projectile system 40 in use within the gun barrel 10 in the embodiment shown the gun barrel 10 has no stops 19 on which the bullet 53 partially rests the bullet 53 in this embodiment with s sabot 51 has been loaded from the muzzle end 15 of the barrel 10 to where the bullet 53 and sabot 51 rest against and mates with an element 44 of a cartridge case 41 the cartridge case 41 which includes the powder 42 and an element 44 the element 44 may be a powder and compression plug 44 or a powder container plug 44 in the embodiment shown the caliber of the chamber 12 is equal to the caliber of the bore 16 additionally the exterior surface of the cartridge case 41 rests on or adjacent to the chamber 12 thus the cartridge case 41 is adjacent to the chamber 12 fig7 depicts a perspective view of one embodiment of an entire firearm 1 employing the gun barrel 10 of the present invention several pieces of the firearm 1 are standard to the art including a stock 6 trigger assembly 2 sights 5 hammer 3 and the like the gun barrel 10 is attached to the rest of the firearm.