M3 submachine gun

, France, August 1944 In 1941, the U.S. Army Ordnance Board observed the effectiveness of submachine guns employed in Western Europe, particularly the German 9×19mm MP 40 and British Sten submachine gun and initiated a study to develop its own "Sten" type submachine gun in October 1942. These original 9 mm guns, identified by the markings U.S. 9 mm S.M.G. on the left side of the magazine well (without any model designation, such as M3), were delivered to the OSS in 1944. The 9mm M3 was also supplied to the French, Belgian, Dutch, Italian and Norwegian resistance groups so that captured German ammo could be used thus reducing the need for .45 ACP ammo resupply drops from the OSS and the SOE. Additionally, Rock Island Arsenal and Buffalo Arms Corporation manufactured parts for a limited number of 9 mm conversion kits for the M3. Though 25,000 kits were originally requested for procurement, this was changed to a recommendation by the Ordnance Committee in December 1943 that only 500 9 mm conversion kits be obtained. The Bell Laboratories suppressor was estimated to be only 80% as efficient as the British suppressed STEN Mk IIS. With its stamped, riveted, and welded construction, the M3 was originally designed as a minimum-cost small arm, to be used and then discarded once it became inoperative. As such, replacement parts, weapon-specific tools, and sub-assemblies were not made available to unit-, depot-, or ordnance-level commands at the time of the M3's introduction to service. In 1944, a shortage of M3 submachine guns created by the need for interim production changes forced U.S. Army Ordnance workshops to fabricate pawl springs and other parts to keep existing weapons operational. , armed with M3 submachine gun in conversation with Capt. John E. Kent, Co. A, 117th Infantry Regiment somewhere in France, fall 1944 After its introduction to service, reports of unserviceability of the M3 commenced in February 1944 with stateside units in training, who reported early failure of the cocking handle/bolt retraction mechanism on some weapons. PFC tanker, armed with an M3A1 submachine gun guards his M60A3 main battle tank during Central Guardian, a phase of Exercise REFORGER in West Germany, January 1985 In the Vietnam War, suppressed versions were made with removable barrels that can be installed after taking a standard barrel out, the former made by Guide Lamp. It was also the initial submachine gun equipping the Delta Force (formed in 1977) who prized it for its impressively quiet performance when equipped with a suppressor. Within a year, the M3A1 had been replaced by the 9 mm Heckler & Koch MP5 submachine gun in Delta Force use, but a few were kept past that date as it was felt that the M3A1 performed better with a suppressor than the MP5. Delta Force M3A1s were fitted with thumb safeties. During the Troubles, some of the M3A1s captured from the Provisional Irish Republican Army by British forces were equipped with suppressors. ==Design details==

The M3 is an automatic, air-cooled blowback-operated weapon that fires from an open bolt. Constructed of plain sheet steel, the M3 receiver was stamped in two halves that were then welded together. The M3 features a spring-loaded extractor which is housed inside the bolt head, while the ejector is located in the trigger group. Like the British Sten, time and expense was saved by cold-swaging the M3's barrel. Features The gun used metal stamping and pressing, spot welding and seam welding extensively in its construction, reducing the number of man-hours required to assemble a unit. Only the barrel, bolt and firing mechanism were precision machined. The receiver consists of two sheet metal halves welded together to form a cylinder. At the front end is a knurled metal cap which is used to retain the removable barrel. The cold-swaged, rifled barrel has four right-hand grooves. M3 and M3A1 submachine guns can be fitted with an optional, detachable flash hider, though none saw any service in World War II. A later production flash hider designated Hider, Flash M9 was produced in time to see service during the Korean War. It proved popular in combat, as frequent night engagements emphasized the need to reduce flash signatures on small arms. In Korea, U.S. soldiers equipped with automatic weapons were taught to look above the flash of their weapon during night firing, a practice that sometimes prevented the detection of crawling enemy infiltrators and sappers. During night combat soldiers are trained to look for the enemy's muzzle flashes and fire in that direction, so having a machine gun with a significantly reduced muzzle flash allowed for better nighttime infiltration and gave soldiers an edge in combat. Projecting to the rear is a one-piece wire stock made from a formed steel rod that telescopes into tubes on both sides of the receiver. Both ends of the stock were tapped and drilled so that it can be used as a cleaning rod. It can also be used as a disassembly tool or as a wrench used to unscrew the barrel cap. The M3's cocking handle assembly is located on the right-hand side of the receiver on the ejector housing, just forward and above the trigger, and consists of nine parts. Unlike the Thompson, the M3 feeds from a double-column, single-feed detachable box magazine which holds 30 rounds and was patterned after the British Sten magazine; the single-feed design proved difficult to load by hand, and is more easily jammed by mud, dust, and dirt than double-column, staggered-feed designs like the Thompson. Plastic (Tenite) dust caps were later issued to cover the feed end of the magazine to keep out dust and other debris. Inland started development of the dust caps in May 1944, and they were formally adopted in November 1944. ==Variants==

M3A1 In December 1944, a modernized version of the M3 known as the M3A1 was introduced into service, with all parts except the bolt, housing assembly, and receiver interchangeable with those of the M3. The M3A1 had several improvements: • Most significantly eliminating the troublesome crank-type cocking lever assembly, replaced by a recessed cocking slot machined into the top front portion of the bolt, letting it be cocked by putting a finger into the cocking slot and pulling back the bolt. • The retracting pawl notch was removed, and a clearance slot for the cover hinge rivets was added. • The ejection port and its cover were lengthened to allow the bolt to be drawn back far enough to be engaged by the sear. • The safety lock was moved further to the rear on the cover. • To make loading the single-feed magazine easier, a magazine loading tool was welded to the wire stock; it also served as a cleaning rod stop. • The barrel bushing received two flat cuts that helped in barrel removal by using the stock as a wrench. • The barrel ratchet was redesigned to provide a longer depressing lever for easier disengagement from the barrel collar. • The spare lubricant clip (on the left side of the cocking lever assembly) was removed, replaced with an oil reservoir and an oiler in the pistol grip of the receiver assembly. The stylus on the oiler cap could also double as a drift to remove the extractor pin. At 7.95 pounds empty, the M3A1 was slightly lighter than the M3, at 8.15 pounds empty, primarily due to the simplified cocking mechanism. Sometime during the 1960s the hard T2 plastic cap was replaced in service with one of pliant neoprene rubber, which could be removed with less noise. Unfortunately, during service in the humid climate of Vietnam it was discovered that the rubber cap caused rust to form on the covered portion of the magazine, while causing loaded ammunition to corrode. During the Korean War, existing M3 guns in service were converted to the improved M3A1 configuration using additional new production parts. During the conversion, armorers frequently removed the M3 cocking handle, leaving the rest of the now-redundant cocking mechanism inside the subframe. Overall, the M3A1 was seen by most soldiers and Ordnance technicians as an improvement over the M3. However, complaints of accidental discharge continued to occur even as late as the Korean War. In 1945, the Guide Lamp factory manufactured 15,469 M3A1 submachine guns before production contracts were canceled with the end of the war. During the Korean War, Ithaca Gun Co built another 33,200 complete guns as well as manufacturing thousands of parts for the repair and rebuilding of existing M3 and M3A1 weapons. T29 Prototype chambered in .30 Carbine. The idea for the T29 was driven by logistical reasons and for a weapon to rival the StG 44 which used an intermediate round. The first two examples used 14 inch barrels whereas the third used an 8 inch barrel. Notable differences of the T29 compared to the M3 SMG was the increased length of the magazine well and magazine release catch to use M1 Carbine magazines. Internal components such as the bolt was cut back 9.5mm to give the front of the bolt 15.8mm diameter round extension and a 12.7mm steel block at the rear of the bolt for weight. The guide rod locating plate ahead of the bolt was made thicker and given a central hole to match the round extension of the bolt. This operation closed the bolt head during the last part of the travel forward striking the cartridge. The mainsprings were also different, a system of two springs were used in the T29 to drive the bolt and also used a shorter stronger spring as a buffer. The ejector was also different as it was spring loaded. Receivers of the T29 were modified from M3 SMG receivers using the same M3A1 layout without the previous damage prone cocking handle. Retractable M3 SMG stocks were used without the integral loading tool. Double column, double feed magazines were easy to load without the use of a speedloader. Ejection port was lengthened for the .30 carbine round with the dust cover acting as a safety. ==Foreign variants and derivatives==

PAM-1 and 2 (Argentina) In 1954, a variant of the U.S. M3A1 submachine gun was designed at the Argentine FMAP (Fábrica Militar de Armas Portátiles) factory in the city of Rosario and put into production the following year as the PAM-1 (Pistola Ametralladora Modelo 1). Constructed of somewhat thinner-gauge steel than the U.S. M3A1, the PAM-1 was in essence a 7/8-scale replica of the U.S. weapon in 9 mm Parabellum caliber, but was lighter and had a higher rate of fire. This was due to an incomplete transfer of all details to Argentina. In service, the PAM-1's thinner sheet steel receiver tended to overheat with extended firing, while the gun itself proved somewhat more difficult to control in automatic fire despite the smaller caliber. Additionally, triggering the weapon to fire individual shots proved difficult owing to the increased rate of fire. Problems with accidental discharges and accuracy with the PAM-1 led to an improved selective-fire version with a grip safety on the magazine housing known as the PAM-2, first introduced in 1963. Type 36 and 37 (China) The Type 36 is a direct clone of the M3A1, manufactured in 1947 at the Shenyang Arsenal in Mukden. It resembles a M3A1, except that it has no flats to allow the use of a wrench for easy removal and it has no oil bottle trap in the pistol grip. Its parts are not interchangeable with the M3A1. Ten thousand Type 36s were made before they were obtained by pro-Communist forces in 1949. The Type 37 is a direct clone of the 9mm-chambered M3, made at the 60th Jinling Arsenal near Nanking. Production continued in Taiwan as the Type 39, a successor to the Type 37. ==Users==

members conduct interdiction training with the U.S. Coast Guard in Cebu City, 2009. Two of them are armed with M3s. • • • : Burundian rebels • • • • : • • : Modifications done on the refurbished weapons include an integral suppressor and a Picatinny rail. The weapon had been tested with a prototype in May 2004. They are known as M3 SpecOps Generation 2. on picatinny rail, integral suppressor and a modified magazine to reduce jamming issues. • : Used by Royal Thai Air Force. • Former • : 623 pieces used by the Austrian Armed Forces. Returned to the USA under the MAP agreement. • : Captured and used in the Korean War by Chinese PVA soldiers. • : Used during World War II by the Free French forces and Algerian War • : Used by the Greek armed forces during World War II and the post-World War II period. • : Used by the JSDF until the adoption of the Minebea PM-9. Known to be used by JGSDF tank crews as a personal defense weapon. All guns retired by 2011. • : Received by the US Government during the Vietnam War 1955–1975. • : Lend-Leased to the National Revolutionary Army, along with the Thompson, to replace the outdated Chinese copies of the MP 18 and MP 28 submachine guns used during the Second Sino-Japanese War and the early years of the Chinese Civil War. Copies made as the Type 36 and Type 37 which the number were named after the Chinese Republican Calendar • : The Army received 748 M3s before the Korean War. The M3 in service with the Army reached 4,565 (December 1950), 7,350 (December 1951), 23,311 (December 1952), and 39,626 (27 July 1953) units. Later used by Special Warfare Command until replaced by K1A SMG. • : Used by the Iranian Imperial Guard. • : Used by Viet Cong and Viet Minh. • • : 9 mm variant supplied to the Norwegian resistance during World War II by the OSS (along with the United Defense M42 submachine gun). • • : In use by British 78th Division after November 1944 and later used by soldiers of 41 Commando in Korea • Non-state actors • Front for Congolese National Liberation • Provisional Irish Republican Army ==See also==