The ShVAK (Russian: ШВАК: Шпитальный-Владимиров Авиационный Крупнокалиберный, Shpitalnyi-Vladimirov Aviatsionnyi Krupnokalibernyi, "Shpitalny-Vladimirov Aviation Large-calibre") was a 20 mm autocannon used by the Soviet Union during World War II.

The TNSh was a version of the gun produced for light tanks (Russian: ТНШ: Tankovyi Nudel’man-Shpitalnyi).

[5] Similarly to its predecessors, the 20 mm ShVAK was a gas-operated gun, belt-fed by disintegrating link ammunition.

[7] The most significant design difference from the ShKAS was that the gas cylinder was moved under the barrel in the ShVAK, giving it a more compact assembly.

[8] The end of the barrel was threaded, and this thread was used to screw on a blast-reduction tube of a length that depended on the installation requirements:[9] One of the outstanding features of this weapon is the method of solving blast tube difficulties, a troublesome problem in all installations of aircraft cannon in fighter aircraft.

The Soviets' simple solution was to thread the end of their standard barrel and then screw on for whatever length was needed a heavy piece of tubing, the bore diameter of which was slightly greater than that of the rotating band of the projectile.

This choice of materials was assumed to be motivated by the desire to allow parts to "deform and bend well in advance of fracture" enabling a safer operation at a high rate of fire, but having the tradeoff of shorter overall lifespan of the gun.

Three Polikarpov I-16 aircraft, all produced in January 1939, were armed with the propeller-synchronized version of the 12.7 mm ShVAK; this short series was given the I-16 Type 16 designation.