Despite the "last gunfighter" moniker, the F-8s achieved only four victories with their cannon; the remainder were accomplished with AIM-9 Sidewinder missiles, partly due to the propensity of the 20 mm (.79 in) Colt Mk 12 cannons' feeding mechanism to jam under G-loading during high-speed dogfighting maneuvers. Between June and July 1966, during 12 engagements over North Vietnam, Crusaders claimed four MiG-17s for two losses. The Crusader would claim the best kill ratio of any American type in the Vietnam War, 19:3. Of the 19 aircraft claimed during aerial combat, 16 were MiG-17s and three were MiG-21s. U.S. records indicate only three F-8s lost in aerial combat, all to MiG-17 cannon fire in 1966, but the VPAF claimed 11 F-8s were shot down by MiGs. A total of 170 F-8 Crusaders would be lost to all causes - mostly ground fire and accidents - during the war.