Turret mounted weapons on the M113 and M113A1 series
FIRE SUPPORT VEHICLES
The M113 series was an extremely popular carrier for self-propelled weapons. It provided the basic chassis for a wide variety of fire support vehicles, some of which could have been classified as self-propelled artillery, tank destroyers, or light tanks. One proposal mounted the standard 105mm howitzer M2A1 in the open top of the crew compartment on an M113.
A later concept study placed the lightweight XM103 105mm howitzer on top of an M113 using components from the XM104 self-propelled howitzer. Another fire support combat vehicle concept installed a howitzer in the front armor of a modified M113. Firing ports were located in the side walls for the crew and a 7.62mm machine gun was carried on an external mount at the commander's hatch.
A large number of turret mounted weapons were installed on the M113 series both in the United States and abroad. In fact, it seems that anyone with a turret mounted weapon proposed its installation on the M113, no doubt influenced by the large numbers of these vehicles in service worldwide. In Australia, the turret from the Saladin armored car, armed with a 76mm gun, was adapted to the M113A1.
Later, a similar installation used the turret from the British Scorpion reconnaissance vehicle which was armed with a later model of the 76mm gun. This conversion also utilized the M113A1 chassis and the vehicle retained its swimming capacity with the addition of side flotation cells and a high displacement trim vane.
The LP90 Cadillac Gage turret from the V-300 armored car was mounted on the roof of the M113A1. Armed with the Cockerill Mark III 90mm gun and a coaxial 7.62mm machine gun, it was described as the fire support vehicle M113 with 90mm cannon. This 90mm gun had a short 12 inch recoil and weighed only about 1,000 pounds.
The combination of the turret and mount weighed approximately 4,900 pounds including ammunition and a two man crew. The cannon was fitted with a muzzle brake to reduce the recoil force. The total 90mm ammunition stowage was 42 rounds. In addition to the coaxial machine gun, another 7.62mm weapon was mounted on the turret roof.
An agreement between GIAT in France and FMC resulted in the installation of the GIAT TS90 turret on the M113A2. This turret carried the GIAT CS90 90mm gun. An initial concept drawing showed this vehicle with side flotation cells and a high displacement trim vane. However, both were eliminated from the test vehicle.
Development of the 60mm automatic gun by Israeli Military Industries (IMI), resulted in another variant of the M113A1. Designated as the Hyper-Velocity Medium Support (HVMS) weapon system, it was installed in a turret mount on the M113A1.
Firing an armor piercing, fin stabilized, discarding sabot (APFSDS) round at a muzzle velocity of 1,620 meters per second (5,315 feet per second), it could penetrate the front armor of the Soviet T62 tank at a range of 2,000 meters. With a rifled barrel 70 calibers in length, the IMI 60mm gun could fire a three round burst automatically in 1.5 seconds or semiautomatically fire five to six rounds per minute (U.S. Army).
Two designs for the automatic loader were proposed. The first mounted two magazines holding three rounds each on the gunjust back of the breech ring. The second design was more complex with four seven round magazines permitting the use of four types of ammunition. With both designs, the commander was located on the left side of the cannon and the gunner was on the right.