and its main gun, the Modèle F1, a monoblock steel cannon. HEAT warheads suffer when spin stabilized, a product of rifled barrels, causing the French to develop the Obus G, (Gresse). This projectile was composed of two major parts, including the outer shell and a suspended inner shell, separated by ball bearings. This allowed the projectile to be spin-stabilized, and therefore more accurate than a normal fin-stabilized HEAT round, while the inner shell did not spin, allowing the warhead to work at maximum efficiency. The warhead, containing 780 gram hexolite, could penetrate up to of steel armour and was effective against tanks at up to . As it combined a good accuracy with a penetration that was independent of range, it has been considered an "ideal round" for its day The AMX-30 was also designed to fire the OE F1 Mle.60 high explosive projectile, the SCC F1 training warhead and the OFUM PH-105 F1 smoke round. The main gun was coupled with a recoil brake, which had a maximum extension of , and could depress to −8 degrees or elevate to 20 degrees. The turret's firepower was augmented by a coaxial M2 Browning machine gun. The tank commander also made use of a anti-aircraft machine gun on the turret roof. The vehicle carried 50 projectiles, 748 rounds and 2,050 bullets. The tank commander was issued a cupola which offered ten all-around direct-vision episcopes, and a binocular telescope with 10x magnification. The commander was also given an optical full-field coincidence range finder. The gunner was given a telescoping gun sight and two observation periscopes. The production version of the AMX-30 was fitted with Hispano-Suiza's HS-110 diesel engine, located in the rear of the hull. The engine could be replaced on the field in 45 minutes, and produced , offering the tank a maximum velocity of on roads. The fuel efficient engine, in conjunction with a total fuel capacity of , gave the AMX-30 a maximum road range of up to . The engine's drive is taken through a Gravina G.H.B.200C twin-plate centrifugal clutch. The gearbox was an AMX 5-SD-200D, with five forward gears and five reverse gears. This transmission was heavily influenced by that of the German Panther tank and was based on a project which had begun in 1938. The transmission was one of the AMX-30's major faults and caused a variety of mechanical problems, including that the driver would