For some years the Russian Army deployed two 120 mm gun/mortar systems, the 2B16 (NONA-K) towed system and the 2S9 full-tracked self-propelled system.

It is now known that these two weapons share the same 120 mm ordnance and fire the same family of ammunition.

These 120 mm rifled weapons combine the features of a howitzer and mortar in one system. In many respects they are unique weapons as there is no similar system in the West.

Development of the 120 mm 2B16 towed system started in the 1970s at the famous Perm artillery facility and the Central Scientific Research Institute for Precision Machinery Construction.

Actual production of these 120 mm weapons is undertaken by the Motovilikha Plants Corporation based in Perm.

It was accepted for service with the Russian Army in 1986 with the main user being the air assault forces. Within the designation NONA-K the K stands for wheeled.

The 120 mm/24.2 calibre ordnance, designated the 2A51, has 40 constant twist rifling grooves and is breech loaded. It can fire both Russian and Western types of 120 mm rifled ammunition (for example that used by the French TDA 120 RT-61 towed mortar).

The towed 2B16 is fitted with a large muzzle brake but the weapon installed in the 2S9 and 2S23 is not.

The breech mechanism is of the vertical sliding type with plastic gas obturator and a chamber indent device is fitted to retain the round in place when the weapon is fired at high elevation.

Ammunition is loaded manually but ramming is automatic. After the loader has selected a round from the ready rack it is placed in a feed tray and after an electric button has been pressed a pneumatically operated rammer automatically seats the round in the chamber and closes the breech.

When the weapon has been fired the breech opens and the rammer bleeds compressed air into the chamber to force fumes from the muzzle.

Types of 120 mm projectiles fired by the 120 mm gun/mortar include HE-FRAG High-Explosive FRAGmentation (HE-FRAG), High-Explosive Anti-Tank (HEAT) and smoke as well as 120 mm mortar bombs Details of the prerifled projectiles are listed in the specifications.

The HE-FRAG projectile is called the OF-49, has a steel body and contains A-IX-2 explosive. There is also the OF-51 HE-FRAG projectile which also contains A-IX-2 explosive.

The rocket-assisted projectile is called the OF-50. The motor cuts in 10 to 13 seconds after the projectile leaves the barrel. The HEAT projectile is fin stabilised and will penetrate 650 mm of conventional armour at 90° to the vertical.

Standard 120 mm mortar bombs fired include the OF-843B, OF-34 and OF-38 high-explosive fragmentation, S-843 and 3S9 illumination, 3Z2 incendiary and 3D5 smoke. These have muzzle velocities of between 119 and 331 m/s and ranges of between 430 and 7,150 m.

More recently a 122 mm laser-guided projectile has been developed called the Kitolov-2 which is claimed to have a kill probability of 0.8 to 0.9.

Russian sources have indicated that this last round, or a modified version of it, can be fired from the wheeled 2S23 and therefore probably the older 2S9. In addition, Russia has developed a 120 mm laser-guided projectile called the Gran.

Artist's impressions show Gran being launched from a muzzle-loaded mortar installed in an MT-LB full-tracked vehicle. Maximum range of Gran is quoted as 7.5 km with the total weight of 25 kg. As far as it is known Gran has yet to enter volume production.

The 2S9 is also referred to as the NONA-S and is based on a modified BTR-D armoured personnel carrier chassis. This in fact entered service as far back as 1981 and saw combat in Afghanistan. This has a similar ordnance to that used in the towed NONA-K.

The latest 120 mm gun/mortar system to enter service is the 2S23, or NONA-SVK which is based on the chassis of the BTR-80 (8 x 8) APC which has been in service with the Russian army for some years.

This uses a modified version of the 120 mm 2A51 ordnance which is called the 2A60, but ballistics and characteristics remain the same.

Like the 2S9, the 120 mm system mounted in the 2S23 is mounted in a turret with a limited traverse of 35° left and right with elevation from -4 to +80°. A total of 30 120 mm bombs is carried compared with 25 for the older 2S9.

In addition, on the roof of the 2S23 is a 7.62 mm PKT machine gun which is connected to the TKN-3A sighting device which allows the weapon to be fired under complete cover,

While the 2S9 and 2S23 have identical firepower capabilities, the main advantage of the latter is its higher road speed (80 km/h compared to 60 km/h), greater operational range and lower life cycle costs than its tracked counterpart, production of which ended some years ago.

Late in 1994 Russia revealed that it had developed a new 120 mm cargo round which can be fired from the 2S23 and presumably the older weapons as well.

This projectile weighs 26 kg and carries 35 HEAT submunitions which have been designed to attack the vulnerable upper surfaces of armoured vehicles and also have an anti-personnel capability. This projectile has a minimum range of 150 m and a maximum range of 11,000 m.

More recently it was revealed that Russia had developed to the prototype stage a new self-propelled weapon called the 2S31. This is armed with a 120 mm gun/mortar with a much longer barrel than that of the 2S9 and 2S23. In addition to firing the same family of ammunition as the 2S9 and 2S23 it also fires a range of enhanced ammunition which like the other natures of 120 mm ammunition, is manufactured by the Bazalt State Research and Production Enterprise.

Production of the 2S9 is complete and it remains in service with the Russian Army. Production of the 2S23 is under way at low rate and it is in service with the Russian Army. It is understood that the People's Liberation Army has taken delivery of a quantity of 120 mm 2S23 systems together with conventional natures of ammunition as well as a laser guided projectile.