The 7.62 mm EX-34 is the smallest member of the The Boeing Company (previously McDonnell Douglas Helicopter Systems and before that Hughes Aircraft Company) family of Chain Guns® and was developed by the company in the 1970s as a private venture, mainly as a coaxial machine gun.
It is the standard coaxial machine gun on the British Vickers Defence Systems Challenger 2 MBT and the Alvis Vehicles Warrior infantry combat vehicle used by the British Army. It is also fitted to the export version of the Challenger 2E MBT which as of mid-1999 remained at the prototype stage.
Virtually all production of the weapon has been undertaken in the UK under licence with the latest contract being awarded by the UK Ministry of Defence early in 1996 to Heckler & Koch (UK), part of British Aerospace Defence Limited, Royal Ordnance Division.
This covered the supply of 606 7.62 mm EX-34 weapons to the British Army, plus spares for delivery from late 1996 through to 1998. In British Army service the EX-34 is called the L94A1 and the UK is the only known user of production weapons for land system applications.
The 7.62 mm EX-34 has also been built for helicopter applications by The Boeing Company as part of the HGS-55 armament system and sales of this were made to Colombia and Kenya.
According to The Boeing Company, the design of the EX-34 provides the optimum solution for gas, blast and feed problems which are often associated with enclosed small calibre machine gun installations.
Like the 25 mm M242 cannon, covered in detail in the Weapons of 20 mm and upward section, the 7.62 mm EX-34 ejects fired cases forwards (overboard) and capitalises on long bolt-dwell time to minimise gas build up in all cupola and turret installations.
Toxic fume emission within the vehicle during firing has been proven to be less than 5 per cent of that found with contemporary, self-powered coaxial weapons.
For the coaxial installation, the weapon is configured to permit barrel change in less than 10 seconds without downloading ammunition. Barrel jacket configuration can be varied to suit the needs of the specific installation and all jacket designs provide for the Quick-Change Barrel (QCB) feature.
The EX-34 has a cyclic rate of fire of 570 rpm with standard 7.62 mm ammunition and during trials with prototype weapons over 500,000 rounds were fired.