Informative video by Armslist Media . However, the heavy machine gun (HMG) featured here is not a DShK (Degtyaryov-Shpagin “Large Caliber”), but is a modern Chinese derivative called the QJC-88.
In the Chinese military service, the QJC-88 is exclusively a vehicle mounted 12.7mm heavy machine gun for the Armor Corp. The Infantry Corp uses a completely different family of 12.7mm HMG that uses direct-gas impingement or direct gas-recoil operation.
The Degtyaryov and Shpagin designs are still alive in the QJC-88. The milled receiver is similar to the DShK, but it’s shorter and has been lightened up. The QJC-88’s feed-tray features the iconic sprocket arm of the Shpagin design. Interestingly, the smaller tangent rear sight is attached to the feed-tray on the QJC-88, instead of the tall flip-up slider-type rear sight that mouns on the receiver of the DShK.
The QJC-88 HMG weighs 40.7 pounds (18.5 kg) gun only, while the DShK HMG weighs 74.8 pounds (34 kg) with receiver and the barrel installed.
The QJC-88’s bolt group mostly resembles that of the DShK but with two big differences. The gas piston up front has more self-cleaning rings and the gas regulator on the barrel is much easier to access than the one found on the DShK. However, the biggest difference is in the locking mechanism. The QJC-88 uses a pair of smaller Kjellman locking flaps (pronounce Shellman, by the way). The Kjellman flaps are smaller with a more complex shape and open from the front, compared to the larger straight-shaped rear opening Degtyaryov flaps.
Another major improvement on the QJC-88 is the ability for a real quick barrel change. The barrel on the DShk is not so quick to change since it requires the use of tools (a wrench and a hammer) to remove the barrel locking bolt. The QJC-88’s barrel also uses a 1-piece combo gas block and front sight, compared to the separated pinned front sight and gas block on the DShK.
A closer look of the QJC-88’s feed-tray shows that it is shorter and has a more compact layout than that of the DShK’s, and it has its sprocket arm forward of the ammo belt slot, as opposed to being located behind the ammo belt slot like the DShK.
The QJC-88 is designed to be vehicle mounted only. Its trigger is attached to a cable extension or an electric solenoid, and the charging handle on this armored vehicle cupola mount is a slot-machine handle-like lever.
The round box on top houses a reflex optical sight. The firing trigger is a cable squeeze-lever, somewhat like the clutch lever on a motorcycle, and it is located on the left side handle bar. The right handle bar is actually also the crank lever for the elevation mechanism.
Overall, the QJC-88 is definitely based on the DShk but with a lot of modernization and weight reduction; very similar to what FN has done with the AN/M2 and AN/M3 series (including all the newer GAU models), which both were developed from the original Browning M2 50-cal heavy machine gun. The AN stands for Army-Navy, and both series were designed for aircraft use with a narrower and lighter receiver, modified bolt and feed-tray.
The newest QJK99 version that is made for remote weapon station (RWS) mount has a very heavy barrel, is completely lacking of any iron sights, and the mechanical trigger has been replaced by an electric solenoid firing mechanism. The cylinder above barrel is likely a remotely operated actuator for cocking and clearing the weapon, and the device’s function is to push back the bolt group while turning the modified ammo belt feeder at the same time.
Larry Vickers on the real DShK:
Now compare that to the W85, which is basically the ground mounted version of the QJC88: