M26 Modular Accessory Shotgun System

The M26 Modular Accessory Shotgun System (MASS) is a developmental under-barrel shotgun attachment for the M16/M4 family of United States military firearms. It can also be fitted with a pistol grip and collapsible buttstock to act as a stand-alone weapon.

Background
The M26 MASS was developed by C-More Systems to meet the requirements of U.S. troops in Afghanistan for a lightweight door breaching and less-lethal delivery system which would eliminate the need to carry an additional weapon such as a pump-action shotgun.

The M26 has been in development at the U.S. Army's Soldier Battle Lab since the late 1990s. The idea was to provide soldiers with lightweight accessory weapons, which could be mounted under the standard issue M16 rifle or M4 carbine. These would provide soldiers with additional capabilities, such as: door breaching using special slugs; very short-range increased lethality, using 00 buckshot; and less-lethal capabilities using teargas shells, rubber slugs, rubber pellets, and other less-lethal rounds.

The original idea has been based on the KAC Masterkey system, dated back to the 1980s, which originally included the shortened Remington 870 shotgun mounted under the M16 rifle or the M4 carbine. The M26 improved the original Masterkey concept with the detachable magazine option and more comfortable handling, thanks to bolt-operated system. The detachable magazine offers quicker reloading and more rapid ammunition type change. The relatively large bolt handle is located closer to the rear than the slide on the pump-action shotgun in the Masterkey configuration, and thus is more comfortable to cycle in combat. The bolt handle can be mounted on either side of the weapon. At the present time, small numbers of M26 MASS shotguns are issued to U.S. troops in Afghanistan. The shotgun is currently in low rate initial production.

Specifications

 * Caliber: 12 gauge
 * Operation: Straight pull bolt-action.
 * Capacity: 5 round detachable magazine.
 * Ammunition: 2.75 and 3 in lethal, less-lethal and breaching rounds.
 * Barrel length: 7.75 in (197 mm) with integral breaching stand-off adapter.
 * Under-barrel version:
 * Overall length: 16.5 in (419 mm)
 * Weight: 2 lb 11 oz (1.22 kg)
 * Stand-alone version:
 * Overall length: 24 in (610 mm) (stock collapsed)
 * Weight: 4 lb 3 oz (1.90 kg)