The MG251 120 mm smoothbore tank gun has been developed by Israel Military Industries to meet the requirements of the Israel Defence Forces and was first revealed in 1989 when it was shown to be the main armament of the Merkava Mk 3 MBT.

This 120 mm smoothbore gun is similar to the German Rheinmetall 120 mm smoothbore gun installed in the Leopard 2 and M1A1/M1A2 MBTs, but has a different recoil system and more compact overall dimensions.

The recoil system consists of an optimised concentric retarder and pneumatic recuperator. The envelope dimensions in the turret do not exceed those of the existing 105 mm M68 rifled tank gun, so allowing it to be installed in narrow silhouette turrets such as that of the Merkava Mk 3. The gun can, therefore, be installed in other MBTs such as the Merkava Mks 1 and 2, M60, M48 and Centurion with minimal modifications to the turret. As of mid-1999, the only production application for this 120 mm smoothbore gun was the Merkava Mk 3 MBT.

The 120 mm ordnance is fitted with a thermal sleeve developed by Vishay in Israel and this is provided with a fume extractor which can be removed for maintenance without disturbing the actual sleeve.

The Israel Military Industries 120 mm smoothbore tank gun fires a family of ammunition developed by Israel Military Industries but can also fire French, German or US 120 mm ammunition if required.

So far there have been no export sales of the Merkava Mk 3 MBT although it was one of the contenders to meet the Turkish Land Forces requirement for a new MBT.

Details of the 120 mm smoothbore gun for the M60A1 are given in a separate entry.

In production. In service with the Israel Defence Forces.