The 3" Gun M5 is an anti-tank gun developed by the US from the T9 3" anti-aircraft gun. In late 1940 the US Ordnance Corps began to adapt the T9 3" Gun to the anti-tank role. The barrel of the T9 was combined with the horizontal sliding block breech, hydro pneumatic recoil system and split-trail carriage of the M2 105mm howitzer.
The prototype test weapon was designated the T-10 and began trials in September 1941. Field trials soon proved the new weapon was a great improvement over existing US anti-tank guns. After a few minor problems were ironed out and it was adopted as the M5 3" Gun on carriage M1.
Few infantry divisions are supported by self-propelled tank destroyers. Instead they leaned heavily on the hard-hitting firepower of the M5 3" guns. These gunners were specially trained to offer the GIs the best anti-tank coverage available.