76 mm gun M1

76 mm gun M1
An M18 Hellcat armed with a 76 mm gun
Type	Tank gun
Place of origin	United States
Service history
Used by	United States
Wars	World War II, Korea
Production history
Designer	US Ordnance Department
Specifications
Weight	1,141 lb (517.55 kg)
Barrel length	52 calibres
Caliber	76.2 millimetres (3.00 in)

The 76 mm gun M1 was an American World War II–era tank gun developed by the U.S Ordnance Department in 1942 to supplement the 75 mm gun on the basic Medium tank M4. It was also used to arm the 76 mm Gun Motor Carriage M18 tank destroyer.

Tested in early August 1942 and classified on August 17, 1942, it was not until August 1943 that the Ordnance Department developed a mounting for the M4 tank that the tank forces would accept. It was not accepted for combat until July 1944. In January 1943, the decision was made to mount the 76 mm on the vehicle that would become the M18. By May 1944, it was being combat tested as the T70.

The development of a better weapon than the 75 mm gun was foreseen before the U.S. had combat experience with well-armored German tanks. The original Military specifications of 11 September 1941 for the M4 tank allowed for the mounting of numerous weapons including the 3 inch gun. The first specimens of the weapon that was to become the 76 mm Gun M1 were being evaluated in August 1942 while the U.S. did not enter the ground war in the European/Africa region until Operation Torch in November 1942.

The 3 inch gun was considered too heavy at about 1,990 lb (900 kg). New stronger steels were used to create a weapon weighing about 1,200 lb (540 kg). It was a new gun with a breech similar to that of the 75 mm M3 Gun but with a new tube (barrel and cartridge chamber) design to accommodate a new cartridge. It fired the same projectiles as the 3-inch (76 mm) M7 gun mounted on the 3in Gun Motor Carriage M10 tank destroyer and towed 3-inch Gun M5 anti-tank gun, but from a different cartridge case. The "76-mm" designation was chosen to help keep the supply of ammunition from being confused between the two cannon. The 76 mm also differed in that successive models received a muzzle brake and faster rifle twist.