XM-26 LSS (lightweight shotgun system) (USA)

 Early variation of the XM-26, mounted below the barrel of the M4A1 carbine.

 the latest (current) version of the XM-26 LSS mounted under the M4A1 carbine.

 XM-26 LSS with detachable pistol grip / shoulder stock and hand guards, to beused as a standalone weapon.

 XM-26 LSS as a stand-alone shotgun weapon, with box magazine inserted.

Type: manually operated, straight pull bolt action
Gauge: 12
Length: 420 mm as an attachment weapon; 610 mm as a stand-alone weapon(with stock collapsed)
Barrel length: n/a
Weight 1.02 kg as an attachment weapon; 1.9 kg as a standalone weapon
Capacity: 5 rounds in detachable box magazine

The XM-26 Lightweight Shotgun System has been in development at the US Army's Soldier Battle Lab since late 1990s. These shotguns are manufactured by the C-More Systems company. Theidea was to provide soldiers with lightweight accessory weapon, which could be mounted under the standard issue infantry rifle (M16A2 or M4A1 carbine), and provide soldiers with additional capabilities, such as: door breaching using special slugs; very short-range increased lethality, using 00 buckshot; less-lethal capabilities using tear gas shells, rubber slugs and buckshot, and other less-lethal rounds.The original idea has been based on the Masterkey system, dated back to 1980s,which originally included the shortened Remington 870 shotgun mounted under the M16 rifle or carbine. The XM-26 improved the original Masterkey concept with the detachable magazine option and more comfortable handling, thanks to bolt-operated system. 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. Bolt handle could be mounted on either side of the weapon. At the present time small numbers of XM26 LSS shotguns are issued to US troops in Afghanistan, and, according to available sources, these  weapons are well received by troops who used them. It is believed that XM-26 will be compatible with the next US assault rifle, the XM8.

XM-26 is a modular, manually operated, straight pull bolt action shotgun. The barrel is locked [probably] using the rotating bolt, the bolt handle could be mounted on either side of the bolt for ambidextrous handling. XM-26 is fed using detachable box magazines which hold five rounds of 12 gauge ammo. Short barrels are fitted with special muzzle devices. By default, XM-26 has no sights; when mounted under the rifle or carbine, shooter uses rifle sights to aim the attached shotgun. When XM-26 is used in standalone mode, it is equipped with detachable pistol grip and M4-style collapsible buttstock, and small handguards around the barrel. integral Picatinny rail on the top of the XM-26 receiver cant hen be used to mount various sighting equipment.

Special thanks to Kevin Kyle for information

By firearm.com