versus the World War I trench gun version was that the original design, containing six rows of holes in the perforated heat shield, was reduced to only four rows during 1942. During the Korean War, the Marines used the Model 12 extensively. Likewise, the Marines and U.S. Army used the Model 12 during the Vietnam War. However, production of the Model 12 ended in 1964, which led to the Model 12 no longer being purchased by the military. However, there were numerous firearms already in the American arsenal, and the Model 12 would continue to see combat service until the end of the 1960s. During the middle 1960s, the Ithaca 37 shotgun was acquired for combat use, and it began replacing the Model 12 as the primary shotgun employed by the United States military. The Ithaca 37 eventually became the most commonly-used shotgun of the Vietnam War. Other shotguns which were used in that conflict included the Winchester Model 1897 trench gun, the Stevens Model 77 shotgun, and the Remington 870 Wingmaster, the latter of which was used more by the U.S. Navy than other branches. Unlike most modern pump-action shotguns, the Winchester Model 12 had no trigger disconnector. Like the earlier Model 1897, it fired each time the action closed as long as the trigger remained depressed from the prior shot. While the trigger remained depressed, as fast as one could pump the action open and closed another round would fire ("slam firing"). That capability and its 6-shell magazine capacity made it effective for close-combat. See List of individual weapons of the U.S. Armed Forces Users : Used by 1st Paratroopers Brigade (Greece). See also Combat shotgun Riot shotgun List of shotguns Winchester Model 1897 References Fawcett, Bill. Hunters & Shooters: An Oral History of the U.S. Navy SEALS in Vietnam. NY: Avon Books, 1995. , pp. 79–80, especially. "Give Us More Shotguns!" by Bruce N. Canfield, American Rifleman, May 2004 "Sequence of Take-down and Assembly Operations Model 12 Slide Action Repeating Shotgun", A. A. Arnold, Olin, Winchester-Western Division, New Haven, CT, October 1957 External links GlobalSecurity.org – Military use of shotguns Pump-action shotguns United States Marine Corps equipment Winchester Repeating Arms Company firearms World War I infantry weapons of the United States World War II firearms of the United States Shotguns of the United States Takedown guns Weapons of the Philippine Army