Hill Submachine Gun

Developed by engineer and inventor John L. Hill the Hill H15 submachine gun was decades ahead of its time. Hill began developing the idea for his futuristic looking gun in the late 1940s but it wasn’t until the early 1960s that he built his first prototypes. 

The H15 fed from unique clear plastic single or double stack magazines which were loaded into the top of the receiver. This magazine was preloaded and sealed with an aluminium cap and magazine capacity varied with length. The H15 was chambered in 9x19mm and .380 ACP and was intended to be fired as a pistol. Its rate of fire was approximately 400-500 rpm making it quite controllable. It did not have a semi-automatic capability and had very few controls with a non-reciprocating charging handle and an unusual ambidextrous crossbolt safety with the safe position in the centre. 

Hill’s patent for ‘Gun with ejection through hand grip’ shows how the magazine interfaces with the ‘transfer disk’ which positions the cartridge ready for the bolt to chamber and subsequently eject. (source)

The visual similarities to the FN P90 are obvious. They both utilise a horizontal, longitudinally mounted feeding system. The main difference being that a ‘transfer disk’ or ‘turntable’ feeding system (seen in images #5 & #6) is incorporated into the action of the H15 rather than the magazine as with the P90, which has a spiral feed ramp rather than the ‘turntable’. Another shared characteristic is the weapons’ ejection, both drop spent cases from the bottom of receiver through the grip. These similarities are more than coincidence however, Hill was invited to the FN factory in Liege in 1963 and a prototype of his submachine gun was left with FN for a number of years and was no doubt photographed and examined before being returned. It is very likely that design cues if not specifics were taken from Hill’s design as two of Hill’s patents are cited in FN’s patent for the P90′s feed system. 

This patent shows that Hill’s early designs also had side mounted magazines (source)

The H15 weighed approximately 4.5 lbs unloaded with a metal receiver and plastic grip. In December 1953 Hill’s design was examined by the US Ordnance Corps at the Springfield Armory. This example had a more conventional wooden stock with the trigger moved to the rear but still ejecting downwards near the front of the stock. Interestingly the prototype appears to use an instantly recognisable MP40 barrel. It is believed that 4 or 5 of these variants were produced specially at the Frankford Arsenal in Pennsylvania. Other manufacturers were also approached with FN initially interested in the design however the project was dropped in 1965 due to lack of customer interest. At the time FN were producing licensed versions of Uziel Gal’s Uzi submachine gun. Colt were also approached estimating that the gun may cost $30-40 to produce.

A Hill H15 compared with an Uzi submachine gun (source)

The Ordnance Corps was uninterested in the design, no doubt because thousands of M3 submachine guns were still in inventory. Attempts were made to interest law enforcement agencies but the H15 never entered service with any agency or military. Hill was granted a series of patents from 1953 into the early 1960s covering elements of his design with individuals and private manufacturing companies purchasing them. Production of Hill’s design has never been attempted at a large scale and of the 100 or so built perhaps only a dozen remain in working order today. Hill himself (pictured above) died in 1991 at the age of 96.

This post is part of the ‘Inventors and their Guns’ series read about other inventors here.

Sources:

Hill’s Patents: 1 2 3 4 5 6

The Hill Submachine Gun, Small Arms Review (March 2004), B. Pilgrim (source)

H-15 Prototype Submachine Gun (source)

Springfield Armory/Ordnance Corps Photographs: 1 2 3 4

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