China North Industries Corporation (NORINCO) has developed an upgrade package for the widely deployed Chinese Type 59 and Russian T-54/T-55 MBT that includes the replacement of the current 100 mm rifled tank gun by a 120 mm smoothbore gun. When fitted with this 120 mm smoothbore tank gun the Type 59 MBT is also referred to as the T-59 Kai.

As in the past, the exact origins of the Chinese 120 mm smoothbore is not known, except for the Western 105 mm rifled tank gun. All Chinese tank guns have been of Eastern design; these are the 100 mm rifled tank gun and more recent 125 mm smoothbore gun which is fed by an automatic loader.

The latter is fitted to the Type 90, Type 85-IIM and Type 85-III MBTs and has enabled the crew to be reduced to three, commander, gunner and driver.

Some years ago China did develop and place in production the 120 mm self-propelled anti-tank gun Type 89 which has a similar 120 mm smoothbore gun and the 120 mm weapon for the Type 59 upgrade is probably identical.

The 120 mm smoothbore gun is 6 m long and weighs 2,600 kg complete with breech mechanism. It is fitted with a fume extractor and thermal sleeve but has no muzzle reference system. To give an increase in barrel life the interior is chrome-plated.

As well as firing Western natures of Armour-Piercing Fin Stabilised Discarding Sabot (APFSDS) ammunition, such as the German Rheinmetall DM23 and DM33 and HEAT multipurpose, it can also fire 120 mm ammunition developed by NORINCO.

Like the Western 120 mm smoothbore ammunition, this has a semi-combustible cartridge case, all that remains after firing is the stub cartridge case. The penetrator has a respectable length-to-diameter rate of 25.2/1 and complete with saddle weighs 7.33 kg. When in flight the penetrator weighs 4.1 kg.

The NORINCO APFSDS round has a muzzle velocity of 1,660 m/s and is claimed to have a similar armour-penetration performance to NATO natures of ammunition, for example around 550 mm of Rolled Homogenous Armour (RHA) at a range of 1,500 m.

More recently another 120 mm round has been developed under the designation of the 120-11.

This has a total weight of 22.5 kg with the projectile weighing 7.4 kg. This has a muzzle velocity of 1,725 m/s and will penetrate 600 mm of RHA at 2,000 m.

Turret traverse is 360° with weapon elevation from -5 to+18°. A total of 28 rounds of 120 mm ammunition is carried compared to 34 rounds of 100 mm.

To improve first-round hit probability a simplified fire-control system has been fitted which includes a laser range-finder. This enables the upgraded tank to engage moving targets when it is stationary, quoted engagement times are around 7 seconds for a stationary target and 10 seconds for a moving target.

Range, target horizontal angular speed and tilt angle of the 120 mm gun are input automatically, while charge temperature, ambient air temperature, muzzle velocity and cross wind are entered manually as required.

While the weapon is normally laid onto the target by the gunner, if required the commander can also take over, aim and fire. Various types of night vision equipment can be fitted as required by the user. This can be of the image intensification type or of the thermal type.

The secondary armament remains the same and consists of a roof-mounted 12.7 mm machine gun, 7.62 mm coaxial machine gun and a 7.62 mm machine gun which is fixed in the glacis plate and operated by the driver.

Production.