3.7-inch Gun

The 3.7-inch Gun was an anti-aircraft weapon introduced into the British Army in 1938 and adopted by the Canadian Army during the Second World War.

History

After the First World War, anti-aircraft guns became a large concern of many of the world's armies. Not only had aircraft operated tactically during the war, but strategic airpower also was developed, including both dirigibles and multi-engine aircraft used to drop bombs on cities. Initial development of a 3.6-inch gun was abandoned as other ideas were pursued, and in 1928 a specification was set forth calling for a 3.7-inch gun firing a 25-pound shell. It was not until 1933, however, that a firm specification was set out, and both Vickers and Woolwich put forth competing designs in 1935. In April 1936, Vickers, who won the competition, had their pilot gun pass acceptance tests, and production guns began delivery in Jan 1938. Production continued in the UK until 1945. Initial orders with Canadian firms were placed in 1941 for the creation of 206 mobile 3.7-inch Guns, and production in Canada eventually reached 300 guns a month.

The guns were technically advanced, incorporating the possibility of electric data transmission. The gun was heavy, but some initial resistance by British gunners used to the 3-inch guns in existence was soon overcome by the increased performance. Another feature of the gun was an automatic fuze setter; instead of setting each shell's time fuze (which determined the altitude at which the shell would explode) by hand, the round was dropped on to a tray, where an operating flap (called a "pig's ear" due to its shape) was depressed, where after the fuze setter slid over the nose of the shell, set the fuze, then retracted allowing the tray to move the round into place where an automatic rammer put the gun in the breech, which closed automatically.