DShK Heavy Machine-Gun (Soviet Union)
Designed by Kolesnikov, this mount consists of a detachable two-wheel base and three folding legs, which form the tail-boom for ground applications and are extended to form a tripod for AA applications. Kolesnikov mounts were issued with heavy armored shields, but crews often discarded shields to save some weight and to decrease the gun profile when firing from wheels.
In the AA role, both wheels and shield were detached from the mount, and an optional shoulder support can be installed.
The DShK is a 12,7mm gas operated, belt fed, air cooled machine gun that fires from an open bolt and in automatic mode only. The gas piston and chamber are located below the barrel; the gas piston is of the long stroke type, and is attached to the bolt carrier. The gas chamber is fitted with a gas regulator, which requires a special wrench to make adjustments. The bolt, of generally rectangular cross-section, locks into the receiver with two outwardly pivoting flaps. These flaps are pushed outwards from the bolt to lock it by the enlarged firing pin, which in turn is operated by the vertical projection on the bolt carrier. The rear of the receiver houses two spring buffers, one for the bolt and one for the bolt carrier.
The heavy barrel is finned for better cooling, and is fitted with a large muzzle brake. The barrel can be detached from the weapon as it is screwed into the front of the receiver, and then fixed there by the cross-bolt, which is also screwed in place.
On DShK guns, the belt feed uses a simplified slider-type belt traction unit, also powered through the swinging arm, and somewhat similar in design to the feed of the RP-46 gun. Spent cartridges are ejected down through openings in the receiver and bolt carrier. In manual (ground and AA) applications gun is fitted with dual spade grips at the back of the receiver, and a dual trigger. Charging handle is also shaped as a spade grip, and is located horizontally below and between spade grips. Standard sighting equipment is an open sight adjustable for range (up to 3500 m in 100 m increments) and windage. Additional anti-aircraft sights can be installed for AA use.
The 12,7 x 107mm cartridge was introduced in the Soviet Union in1934. The round was used in the DShK machinegun in 50 round belts and designed for anti aircraft use or for use against light armored ground targets. The muzzle velocity was 860 - 880m/s and the operation temperature could vary from -50°C to +50°C. The barrel has 8 right-hand grooves resulting in an improved fire-rate of 750rpm. The 50 round ammunition-belts used a linkage of 3 x B-32 to 1 x BZT-44 (3 API to 1 API-T). These bullets have the following armour-piercing effect:
90% of all bullets penetrate a 20mm thick armor plate at 100m. The capability of the tungsten carbide core bullet BS is said to be about 7 times higher than standard bullets. 75% of all bullets ignite the petrol placed behind the 20mm armor plate.The HEI bullet, the MDZ is used specifically for Anti-Aircraft purposes.
Ammunition is exported from the USSR to 49 countries world wide but this type of is also manufactured in Bulgaria, China, the former Czechoslovakia, Egypt, Iran, Pakistan, Romania and Yugoslavia.
The propellant consists of 17,5 to 19,0g of smokeless powder designated as "4/7 Tsgr" powder.
Eighty cartridges are packed in a sealed metal box with two of these boxes per wooden container. These sealed metal boxes have the caliber, type of bullet, Lot Number, number of rounds and type of propellant painted on them. The metal boxes measure 480x350x160mm and weigh 29kg.