Experimental Model 2 submachine gun

The was a pre–World War II experimental submachine gun of Japanese origin chambered in the 8mm Nambu round.
History.
The Type 2 was a development of the earlier Type 1 submachine gun, designed in response to criticisms of the Type 1's awkward ergonomics. The Type 2 offered a more conventional magazine feed and stock, but wholly retained the Type 1's method of operation and was essentially the same gun in a different body. It was initially produced in the mid-1930s and was tested by the Imperial Japanese Army, but rejected. During World War II, an urgent demand for automatic infantry weapons saw the revival of several experimental weapon projects, including the Type 2 submachine gun. Small numbers of Type 2s were produced during this period to meet demands and were issued to Japanese infantry, both in the Pacific and in China, resulting in samples being captured by Allied forces. The British and US Armies studied the weapon after the war, whilst Mukden Arsenal in China reverse-engineered captured examples and produced a copy known as the Mukden Type 2, which was operationally identical but chambered in .45 ACP rather than 8×22mm Nambu.
Design details.
The Type 2 was a blowback-operated submachine gun that fired from a closed bolt. Much like the Type 1, the Type 2's return spring enveloped the barrel of the gun rather than behind the bolt. The front section of the receiver and barrel shroud would travel back with the bolt upon firing and be pushed back forward by the return spring. The barrel stayed stationary. The cocking handle was not located in a slotted groove but instead took the form of a protruding tab fixed to the left side of the receiver. Early pre-war prototypes of the Type 2 were built with the same pneumatic buffer device seen on the Type 1, which cushioned the action of the gun and acted as a bolt delay. The timing of the delay could be adjusted by changing the air pressure exerted by the buffer, thus lowering or increasing the fire rate. This was done by turning a pressure valve located underneath the rear cap. The later wartime models omitted the air buffer feature in an attempt to cut the expensive production costs. The Type 2 typically issued with 30-round magazines, although it could also feed from the same 50-round magazines as the Type 1. Late-war examples of the Type 2 had bayonet fittings, a feature not present on the original production models. A spike bayonet was also designed for the gun but was not used on the production models. The finish of the late-war models was typically poor compared to the earlier pre-war prototypes.