Mossberg 12 Ga Special Purpose/18 1/2 Cylinder Bore Barrel w/Muzzle Brake All Mossberg 930 Special Purpose shotguns feature a self-regulating gas system that vents excess gas to aid in recoil reduction and eliminate stress on critical components. All 930 autoloaders chamber both 2 3/4 inch and 3-inch 12-gauge shotshells with ease from target loads to non-toxic magnum loads to the latest sabot slug ammo. Magazine capacity is up to 7+1 on models with extended magazine tube 4+1 on models without. To complete the package each Mossberg 930 includes a set of specially designed spacers for quick adjustment of the horizontal and vertical angle of the stock bringing a custom-feel and fit to every shooter. Safety and safe handling is of paramount importance in special purpose firearms and the 930 was engineered with that in mind. The receiver-mounted safety is convenient for right or left-handed users simply push the button forward to take the weapon off safe. A protruding chrome cocking-indicator button is strategically placed in the front inner-edge of the trigger guard making it easy to see and feel when the weapon is cocked or un-cocked. Unloading has been made easier too with the Mossberg EZ-Empty system. By depressing the bolt release the carrier can be pushed up and the first shotshell in the magazine removed. Simply repeat until the magazine is empty. All 930 Special Purpose models feature a drilled and tapped receiver factory-ready for Picatinny rail scope base or optics installation. 930 SPX models conveniently come with a factory-mounted Picatinny rail and LPA/M16-Style Ghost Ring combination sight right out of the box. Other sighting options include a basic front bead or white-dot front sights. "