3-inch Gun M1918 - History of The 3-inch M1918

History of The 3-inch M1918

For mobile use the original coastal gun was too heavy, so a smaller version was developed as the 3-inch M1918. For this role the barrel was cut down in length, to 50 calibers from 55, and a new breech was introduced to fire smaller rounds (76.2x585R, 212 cubic inches instead of 76.2x690R, 293 cubic inches). Like the adaptation that created the M2, the M1918 was also fitted with a removable liner in 1928, becoming the 3-inch M3. Another upgrade was started in 1931 as the T8, and then T9, but these projects were cancelled in 1938 when the 90 mm gun was selected in their place.

In September 1940 a project started to adapt the 3-inch gun to the anti-tank role, starting with the T9 experimental model but equipping it with the breech, recoil system and carriage borrowed from the 105mm M2 howitzer. The gun was accepted for service as the 3-inch M5.

A similar derivative of the T9 - the 3-inch M6 - was intended to be mounted on the M5 self-propelled gun, which was eventually abandoned. A final adaptation was the 3-inch M7, which included minor modifications for mounting on the M10 Wolverine. M7 saw wide use although it was supplanted to some extent by more powerful weapons such as the 90mm M3 and the British QF 17 pounder. 6,824 M7 guns were manufactured.