The first Bf-109G "Gustav" entered service in March 1942. New features were a pressurized cockpit with three larger guns mounted on the nose and none on the wings but could be field mounted. The Bf-109G could overheat causing oil leaks; starting a fire forcing the pilot to bail out. The Gustav was produced in many variants including long-range fighters, recon fighters and bomber destroyers. The Bf-109G-6 lacked a pressurized cockpit but was the most numerous Bf-109 produced and the first to carry 13mm machine guns; equivalent to the American 50 caliber Browning. In 1940 Erich "Bubi" Hartmann joined the Luftwaffe and in 1942 was posted to JG 52 on the Eastern Front. Flying with some of the most experienced pilots Hartmann soon developed his formidable tactics. On October 29, 1943; having scored 148 victories; Hartmann was awarded the Knight's Cross. On August 25, 1944 he was decorated with the Knight's Cross of the Iron Cross with Oak Leaves, Swords and Diamonds having a total of 301 victories. By the end of WWII Hartmann had 352 victories; all on the Eastern Front. Soviets called him the "Black Devil".