A number of manufacturers have developed modernisation packages for the old US 155 mm M114 towed howitzer, that utilises a 155 mm 39 calibre ordnance. The development of the 155 mm M114 towed howitzer itself can be traced back to the 1930s.

The upgraded Soltam M114S utilises a 155 mm 33 calibre barrel, enabling a standard 155 mm M107 HE projectile to be fired to a maximum range of 18,300 m, compared with 14,600 m of a standard M114 and 18,100 m when fired from a 39 calibre barrel.

The conversion can be carried out in the user's own facilities using a kit supplied by Soltam, or the weapons can be returned to Soltam for the upgrade work. As far as is known, this upgraded weapon is not used by the IDF.

The 155 mm 33 calibre version does not require such extensive modifications to the existing weapon as the 39 calibre modernisation packages and, according to Soltam, it is a more cost-effective solution.

The new 155 mm 33 calibre barrel has a high-efficiency muzzle brake and is fitted with the original breech ring and breech mechanism of the M114. The new ordnance has a constant 1:20 twist rifling with 48 lands and grooves. The muzzle brake is the same as that fitted to other Soltam 155 mm towed artillery systems.

The cradle remains unchanged although a front bushing has to be added by inserting a new bushing into the original one without the need for extensive machining. The existing spring-loaded equilibrators remain untouched but its upper location is changed, using new brackets bolted to the original points on the saddle.

All other assemblies and components remain untouched, as well as all of the integrated logistics aspects.

A loader assist device based on a pneumatic ramming piston is provided as an add-on kit. The loader assist device enhances the rate of fire and its accuracy as well as easing crew workload by reducing the need to lower the gun for loading. The cylindrical air cylinderfor the pneumatic rammer is mounted on the right trail.

The conversion kit includes the following:

(1) 155 mm 33 calibre tube and muzzle brake

(2) Pneumatic ramming system and its installation

(3) Mounts and fixtures kit

(4) Direct firing telescope as an option

(5) Upgrading instruction and technical data pack

The Soltam upgraded M114 can fire all of the standard 155 mm types of ammunition in worldwide use, starting with the M107 family of ammunition and ending with the more recent Extended Range Full-Bore Base Bleed (ERFB-BB) long-range ammunition family.

The following ranges are obtained:

• M107 projectile - 18,300 m

• M56 projectile - 19,100m

• ERFB-BB projectile - 22,500 m

Due to the improved gun balance, six crew members are enough for the deployment of the M114S instead of the eight crew members of the original M114.