Jackhammer combat shotgun – the unique automatic shotgun

Jackhammer Combat Shotgun 1
Jackhammer Combat Shotgun (Photo: Gun Wiki)

The Jackhammer Combat Shotgun is an automatic, gas-operated, 12-gauge shotgun that uses a pre-loaded rotating cylinder as its magazine. The cylinder has grooves incised on its outer surface which is engaged by a stud on an operating rod, so that as the rod moves back and forth, so it rotates the cylinder.

Design of Jackhammer Combat Shotgun

This is a very similar system to that employed in the Webley-Fosbery automatic revolver. The barrel is floating and is driven forward by gas pressure as each shot is fired. It is then returned by a spring and gives movement to the cylinder-operating rod. This movement of the barrel also disconnects the barrel from its gas-tight seal with the cylinder, allowing the cylinder to be turned to bring the next chamber inline; on the return stroke, the barrel reseals itself into the chamber mouth.

The barrel, flash eliminator, return spring and ‘Auto bolt’ (the patented name for the cylinder operating rod) are all of the high-quality steel. The rest of the weapon is almost all of the synthetic material, new material by DuPont called Rynite SST.

Jackhammer Combat Shotgun - a 12-gauge automatic gun
Jackhammer Combat Shotgun – a 12-gauge automatic gun (Photo: XY)

The cylinder, called by the markers the ‘Ammo Cassete’ is also of Rynite SST, contains 10 cartridges and is sealed with a shrink-film plastic, color-coded to indicate the type of ammunition loaded. The seal is removed by a pull-strip and the cassette slips straight into the weapon and engages the operating system. The weapon is then cocked by the sliding action of the fore-end and is ready to fire. Once the cassette has been emptied, a simple movement of the fore-end releases it to fall clear and allow a new cassette to be loaded. It is not possible to load single cartridges into the weapon, and empty cases are not ejected while firing.

A de-cocking lever, inside the butt-stock, allows the hammer to be safely lowered when the gun is loaded; it can then be carried quite safely. When required, the hammer can be re-cocked silently by using the same lever.

Ammunition (Cartridge)

Although the chambers are for the standard shotgun cartridge, the receiver has been strengthened so that a specially-developed cartridge known as the ‘Jack Shot’ can be fired. This special cartridge operates at a much higher pressure than sporting ammunition and allows special loadings such as flechettes, armor penetrators, preformed fragmenting projectiles or canister loadings, or even simply larger charges of conventional lead shot to be fired safely.

The development of the Jackhammer combat shotgun has now been completed, and the weapon is being studied by various official agencies. Meanwhile, the company is working on more specialized ammunition options and a sound suppressor which will be relatively inexpensive and can be discarded after a limited life.

Technical specifications: Jackhammer Combat Shotgun

Manufacturer: Mark Three, Albuquerque, New Mexico, USA
Type:  Automatic revolver, gas-operated
Gauge: 12
Barrel: 20.6in (525mm)
Weight: 10.07lbs (4.57kg)
Magazine capacity: 10 rounds
Cyclic rate of fire: 240 rounds/minute
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