Notes: Developed at first as a breaching and close-assault attachment for the M-4 SOPMOD carbine, the MASS (Modular Accessory Shotgun System; originally called the Lightweight Shotgun System or LSS) is being developed into a standard attachment for certain members of infantry squads. It is currently being fielded by US special operations units, and tested by certain light infantry units, and has seen operational use by Special Forces and the 10^th Mountain Division operating in Afghanistan and Iraq; in particular, 10^th Mountain is known to be employing at least 200 of these weapons for advanced field testing.

The MASS is a magazine-fed, bolt-action shotgun that can be used as an underbarrel attachment for the M-16, M-4, and the SCAR series of assault rifles, or used as a standalone weapon with the addition of a snap-on gripstock. (C-MORE has also devised a device they call the Quad-Rail, which allows it to be attached to several more NATO and Western assault rifles and carbines.) The MASS has a large standoff muzzle device for blowing hinges on doors; this also doubles as a flash suppressor. (The MASS can be used without this device, if desired.) When mounted on an assault rifle, it is fired in a similar manner to the M-203, with the magazine of the rifle being used as a grip for the shotgun. Soldiers tend to be impressed with how light the MASS is – lighter than the M-203. The MASS can fire virtually any sort of shotgun ammunition of 2.75" or 3" size – the push-feed system even allows for individual feeding of ammunition, if necessary. The bolt operation can be reversed if necessary for left-handed users. Magazines of various sizes have been developed, but they are box-type and the larger ones can be a bit unwieldy. The MASS is designed for use with a variety of combat sights already in common use by the US military, such as the reflex and low-magnification sights which are becoming more common on US military assault rifles and carbines. The MASS itself has no sights of its own.

When used without a rifle, the MASS has one of two gripstocks attached. One is a simple pistol grip, to produce a very compact weapon (known as the MASS A-2); the other uses a pistol grip and sliding stock similar to that of the M-4, with a short handguard (known as the MASS M-4).

As of 2008, the MASS is still considered an experimental weapon, but batches are being hurriedly shipped to Iraq and Afghanistan, in such numbers that a full "M-26" designation cannot be far off. The first unit to be equipped with the MASS as a standard weapon is to happen in mid-2009. Eventual plans call for the possible deployment of one MASS per squad, or possibly one per fireteam.

Notes: This is an unusual bolt-action shotgun with a detachable magazine. It is designed for 3" magnum ammunition, and cannot chamber other sizes of 12-Gauge ammunition. The DL model has a 28" Barrel; the GDL uses a long 36" barrel.

Notes: This is a relatively rare type of firearm, a lever-action shotgun. It is a conversion of the old Model 94 rifle. The power is limited, with its small caliber and short shells, but it is a gun designed for recreational shooting, sort of a shotgun counterpart to a plinking rifle. It has TRUGLO high-visibility sights to make aiming easier. (The sights are said to be distracting for shot throwing but excellent for slugs.)

The Packer is designed to be a light and easy "carbine" version of a shotgun. It is light and easy to carry and shoot. The Packer Compact is a version of the Packer with a reduced-length stock and lightened construction, designed for smaller-stature shooters. The Ranger is a longer-barreled version, with a 24-inch barrel and a full-length tubular magazine.