Weapons: Mortars will now take the FMS route | ADM July 2013

The Australian Army’s decades-old 81mm mortars are nearing replacement, and it appears to be a foregone conclusion that their successor will be the US-manufactured M252AI weapon now entering service with the US Army and US Marine Corps.

Unsurprisingly, the lead up to Land 136 Phase 1 (Land Force Mortar Replacement) has some history attached.

Preliminary approval for a new long-range 81mm mortar (LRM) to succeed the UK/Canadian developed and UK-manufactured F2 81mm mortar introduced in the 1960s was received in October 2003. A Request for Tender was released in March 2006 for what was expected to be up to 150 LRMs, but this was not proceeded with.

Fast forward to 2010 and 2011, when two market surveys were conducted by the Commonwealth to obtain capability, cost and schedule information from industry to inform development of a First Pass business case for consideration by government.

First Pass was duly received in June 2012, with funding for First Pass to Second Pass work. However, not known until confirmed by a Defence spokesperson while this article was in preparation was that this was on the basis of acquisition via the US Foreign Military Sale (FMS) channel.
Accordingly, further Requests for Information are not being solicited, nor will a Request for Tender be issued.

While some countries continue to rely on 81mm mortar systems the majority of these are vehicle-mounted or transported by vehicle or helicopter, and a clear trend is apparent towards the development and fielding of larger, more potent 120mm self-propelled systems.

The Australian requirement for a man-portable 81mm system that is lighter than the in-service F2, coupled with an FMS acquisition, therefore points the finger directly at the M252AI.

Manufactured at the US Army’s Watervliet Arsenal in New York State, the M252AI is a lighter-weight development of the US M252, which along with the ADF’s F2 is based on the British Royal Ordnance L16 81mm system.

Both the F2 and the M252A1 are smooth-bore, muzzle-loaded weapons consisting of barrel, bipod, baseplate and sight unit. However, overall system characteristics of the M252A1 have been improved and weight has been reduced from 41kg to 32kg while maximum range remains 5,935 metres.

Although the US Army deploys 120mm, 81mm and 60mm mortars, Defence says the 81mm has been identified as meeting Army’s need for lethality, accuracy and range as part of the broader indirect fires network.

Howitzer/mortar mix
According to informed sources, the 81mm/155mm artillery mix was determined by experimentation to best provide the agility and flexibility needed across Army’s mission profiles. The options were any two systems across 60/81/120mm mortars and 105/155mm artillery.

Advances in mortar ammunition, particularly pre-fragmented rounds, have boosted lethality and GPS-guided projectiles will significantly improve accuracy, but Defence says that M800 series ammunition comprising high explosive, smoke, illumination and infrared illumination projectiles will continue to be used for the new mortar system.

This does not necessarily mean a separate project may not decide at a later date to acquire more sophisticated (and expensive) ammunition nor, indeed, that mobile, protected 120mm mortars may not in due course become an attractive option to supplement the army’s unprotected, towed M777 howitzers in the Future Land Force.

Each of Army’s seven battalions currently contains a mortar platoon comprising six 81mm mortars and approximately 35 personnel. This structure will be retained under Plan Beersheba, the restructure of Army’s regular brigades to generate three ‘alike’ multi-role manoeuvre formations.
Additionally, as part of Plan Beersheba, six Army Reserve artillery mortar batteries (each the same configuration as a mortar platoon) have been raised within the 2nd (Reserve) Division. This follows on from the decision in 2008 to re-task Reserve artillery units with mortars rather than more personnel-intensive howitzers.

Mortar targeting is currently effected through a combination of voice and data communications using a M32 handheld mortar ballistic computer, which allows three-man mortar crews to send and receive digital call-for-fire messages and calculate ballistic solutions. As part of Land 136, M32s will be replaced with a more sophisticated lightweight ballistic computer.
The mortar observer will be equipped with the same digital terminal control system purchased for the M777 howitzers, and the mortar command post will be integrated into the digital network.

This will allow mortars to be employed directly by infantry units and to operate within the Joint Fires network using the Fires Battle Management System. Both the F2 and M252A1 are capable of sustained fire of 15 rounds per minute.

Defence has confirmed that the new lightweight mortar will be used in a dismounted role, suggesting an eventual order of around 100 to equip Regular and Reserve mortar units and allow for a training allocation and attrition.
The 21 M113AS4 mortar variants, assuming they’re not in mothballs, will continue to offer a mounted mortar capability, but using the in-service F2 mortar.

Bushmaster mortar carriers (the mortar is not fired from inside the vehicle, but up to five troops, the mortar and 50 bombs are easily carried) will presumably provide mobility as required for those units equipped with the new system.

When dismounted, the F2’s three main components are carried by the three-strong mortar crew. Other soldiers in the unit carry up to two rounds of mortar ammunition according to mission needs, a procedure that Defence says will remain the same with the new system.