Serial production started in August 1951, but large quantity production was delayed in favor of producing more MiG-15s so it was never introduced in the Korean War. It did not enter service until October 1952, when the MiG-19 was almost ready to be flight tested. During production, the aircraft was improved and modified several times. The basic MiG-17 was a general-purpose day fighter, armed with three cannons, one Nudelman N-37 37 mm cannon and two 23 mm with 80 rounds per gun, 160 rounds total. It could also act as a fighter-bomber, but its bombload was considered light relative to other aircraft of the time, and it usually carried additional fuel tanks instead of bombs.