.5 inch Vickers

The genesis of the .5 inch Vickers round was a requirement that arose in the latter part of World War One for a .5 inch cartrdige to fulfill a number of roles.

There were four basic requirements:

- Aircraft machine guns

- Anti-tank rifles

- Tank machine guns

- Anti-aircraft machine guns

Of these the first was perhaps the most urgent. In 1918 Britain was being raided by German Gotha and Giant heavy bombers which were able to sustain a large number of hits from .303 inch ammunition and were also armoured. A round was needed that could deliver a larger load of incendiary or explosive compound to inflict fatal damage to these aircraft.

Eley Brothers were tasked with the design of the new round. They decided to begin by necking the .600 Nitro Express to .5 inch calibre, and initial trials were held with a rimmed case and round nosed bullets. The case was then redesigned with a belt and became the .600/.500 inch, first using the round nosed bullet and then a range of spitzer bullets. Ball, SPG tracer, armour-piercing, Buckingham and RTS/RTT explosive bullets were tested before the war ended. The new round was to be fired in scaled up Vickers and Lewis guns and also in an anti-tank rifle designed by Mr.Godsal at Webley & Scott. (See here)

The rounds were headstamped "ELEY .600/500" and when the case was strengthened slightly and the fireholes modified "ELEY .600/500A".

The Armour-Piercing round had a 570 grain bullet with a propellant charge of 135 grains od Dupont No.16 nitrocellulose to give a velocity of 2,650 feet per second.

Work continued slowly post war, the case was modified again and the belt omitted. By 1922 the case design had been finalised and with a bullet to Design RD 469 this was approved as the .5 inch Ball Mark I.

Illustrated is a 1918 drawing showing Vickers gun chambered for the .600/.500 inch cartridge and fitted for airship mounting.