Picture 1: XM307 ACSW grenade launcher, front view
Picture 2: XM307 ACSW grenade launcher, rear view
Picture 3: XM307 ACSW grenade launcher on field trials
Type: gas operated, belt fed automatic grenade launcher
Overall length: 1328 mm
Weight: 22.7 kg complete with tripod mount and sight / fire control unit
Effective range: up to 2000 m against point targets, 3600 m maximum
Rate of fire: 250 rounds per minute
The origins of the XM307 Advanced Crew Served Weapon (ACSW), also known as XM307 25mm Airbursting Weapon System, lie in the several military documents, published in USA during late 1980s. These documents stated that current small arms have reached its peak in development, and the only currently possible way to increase combat effectiveness and single-shot lethality of such weapons is do develop new guns that will fire air-bursting munitions with programmable fuses. Following these conclusions, US Army initiated development of several so-called Objective weapons; two most famous of these were XM29 Objective Individual Combat Weapon (OICW) and XM307 Objective Crew-Served Weapon (OCSW), currently renamed to Advanced Crew-Served Weapon (ACSW). After much development, the prime contractor for ACSW program was selected as General Dynamics Armament and Technical Products (GDATP). The development team for ACSW also includes General Dynamics Ordnance and Tactical Systems (air-bursting ammunition), Kaman Dayron Inc (programmable fuze) and Raytheon (computerized fire control system). First demonstrated in around 1999 as 25mm OCSW, at the present time (early 2006) the XM307 ACSW is on advanced stages of development, with several prototypes already tested with live ammunition, including air-bursting rounds. Initial plans called for first US Army units to be equipped with 25mm M307 ACSW weapons by 2008; M307 shall replace in service the older weapons like Mk.19 Mod.3 40mm grenade launchers and .50 caliber M2HB machine guns. For added versatility, XM307 can be easily converted to fire .50 caliber machinegun ammunition (12.7x99) with replacement of just 5 parts.
The key to greatly increased combat effectiveness of ACSW system is programmable air-bursting ammunition, which will be used in conjunction with electronic fire control unit. This ammunition will allow to precisely engage enemy personnel in open or in defilade, without the need for direct impact in the target area. Other types of ammunition proposed for XM307 ACSW are HEAT (with required armor penetration up to 5cm / 2in), less-lethal (with tear gas for peace-keeping applications) and training rounds with dummy warheads.
It is obvious that by the year 2008 the XM307 will enter into strong competition with several 40mm air-bursting weapons such as Mk.47 Striker 40, and the outcome of this competition is hardly predictable, as either system has its own merits and downsizes. ACSW is certainly lighter, fires lighter ammunition (allowing to carry more ammo in the same weight), and has longer range. 40mm weapons fire bigger warheads and can use huge stocks of already existing and well developed NATO-standard ammunition of various types, including point-detonating FRAG, HEDP, AP, less-lethal and many others.
XM307 Advanced Crew Served Weapon is gas operated, rotating bolt locked weapon that uses differential recoil system for decreased peak recoil. XM307 is belt fed weapon that fires from open bolt. The differential recoil system means that barrel and bolt group are allowed to recoil within the receiver casing together, against the recoil springs. When weapon is cocked for first shot, bolt is locked open and the entire barrel/bolt group is carried rearwards and also locked there. Upon the pull of the trigger both barrel group and the bolt inside it are released, and the bolt loads the round and locks it in chamber while barrel still moves forward; firing pin is then released immediately, and the recoil from the discharge first has to arrest the forward movement of the barrel group, and then throws it backward with less force than it would in the traditional system with fixed barrel. The belt feed and bolt cycling are operated by conventional gas action. The fire control unit includes zoomable day and night vision channels that output the sight picture to the small display at the rear of the sight. Integral laser range-finder allows for precise range measurement, necessary for automatic point of aim correction and for programming of the air-bursting fuses. XM307 weapon is fitted with dual, ergonomically shaped spade grips with triggers and fire and sight control buttons. Additional buttons are located at the rear of the sight / fire control unit, below the eyepiece. In standard applications, XM307 can be used either on lightweight infantry tripod, or on vehicle mounts, manually or remotely controlled. For vehicular applications, GDATP will develop the dual feed option, which will allow to select the type of ammunition (anti-personnel HEAB or armour-piercing) at the instant before firing.