Jackhammer: The unique automatic combat shotgun

Ian Hogg

The Jackhammer automatic combat shotgun is an automated, 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, it rotates the cylinder.

Design

This is a very similar system to 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 moves 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’s mouth.

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

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

The cylinder, called by the markers the ‘Ammo Cassete,’ is also of Rynite SST, contains ten cartridges, and is sealed with a shrink-film plastic, color-coded to indicate the type of ammunition loaded. A pull strip removes the seal, 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 impossible to load single cartridges into the weapon, and empty cases are not ejected while firing.

Pancor Jackhammer
Pancor Jackhammer (Photo: XY)

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

Ammunition (Cartridge)

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

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

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Technical specifications

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: Ten rounds
Cyclic rate of fire: 240 rounds/minute

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