US Army developing 155mm artillery round

The US Army is continuing work on a 155mm artillery round, the XM1113 Insensitive Munition High Explosive Rocket Assisted Projectile (XM1113 RAP), that will extend cannon range to over 24 miles, it was revealed on 25 August.

The XM1113 RAP, which will replace the ageing M549A1 rounds, is being jointly developed by the Program Executive Office Ammunition and the Armament Research, Development and Engineering Center.

Ductri Nguyen, XM1113 integrated product team lead, said: ‘The XM1113 provides the user with cannon-launched munitions to engage targets out beyond the current 30km capability. The new projectile is currently designed to reach 40-plus km and will be compatible with the existing M1156 Precision Guidance Kit (PGK) that provides near precision strike capability.

‘The XM1113 uses a large high-performance rocket motor that delivers nearly three times the amount of thrust when compared to the legacy M549A1 RAP. Its exterior profile shape has also been streamlined for lower drag to achieve the 40-plus km when fired from the existing fielded 39-caliber 155mm weapon systems.’

The PGZ fuze replaces a standard fuze since it can be screwed into the fuze well of a conventional 155mm high explosive cannon artillery projectile. Troops can thus convert conventional artillery rounds into 'smart' munitions with greater accuracy. The new round uses a reengineered artillery shell shape and increased thrust to extend its range.

The currently-fielded M777A2 howitzer can be used to fire the rocket-assisted projectile. Nguyen said his munitions team will closely work with the Picatinny-based weapon system Integrated Product Team (IPT) to make the XM1113 compatible with future long-range weapon systems.

The traditional TNT inside typical artillery rounds has been replaced by the less-volatile and less-reactive Insensitive Munition Explosive. This explosive is less reactive to outside stimuli such as improvised explosive devices, extreme high temperatures or rocket propelled grenades. It is less likely to detonate if a convoy carrying the rounds gets hit by a rocket grenade.

The XM1113 is currently planned for Limited Rate Initial Production in fiscal year 2022. Its developmental effort is being led by the Non Line of Sight Cannon Artillery Division.