The 40mm single-shot, breech-loading Heckler & Koch HK AG36 ("Anbaugranatwerfer 36") was designed as a possible grenade-launching solution for the next possible American assault rifle. It was further developed and eventually adopted for use by the German Army to complement its HK G36 series of assault rifles which were themselves introduced in 1996. In decades prior, squad-level grenade launching was primarily limited to specialized "grenadier" units who were forced to carry a sidearm or second-line weapon as backup to their primary. During the latter half of the Cold War, several developments came to light in which grenade-launching systems could now be affixed to existing assault weapons with minor modification - the American 40mm M203 series being the prime example of this. The M203 was actually developed to replaced the hand-held, single-use M79 grenade launchers fielded during the Vietnam War. The AG36 was developed to fit this same role though, unlike its chief American competitor, the AG36 sports a fixed pistol grip and separate iron sights which allows the weapon to be used free of the assault rifle as needed.
Design of the AG36 is quit conventional for its given role. The weapon is chambered for the 40x46mm grenade and features a folding ladder sight offset to the left which allows for accurized ranged fire against "soft" targets. The firing action involves the insertion of a live 40mm grenade into the breech (the barrel assembly tilts open to the left side), closing the breech and actuating the integrated trigger unit; loading is manual and limited to single shots. Muzzle velocity is approximately 250 feet per second while overall weight is 3.3lbs (1.5kg). The AG36 can accept an optional shoulder stock which assists in operating the unit apart from the traditional assault rifle mounting. Additionally, optical accessories such as laser aimers can be affixed to the launcher which further broaden its tactical value in-the-field. Construction of the unit is in line with general HK practice of the time - lightweight polymers and reliable aluminum - which allow for a lightened overall load, especially when paired to an already-weighty assault rifle system. The AG36 features a general safety mode near the operating thumb area and can be brought to bear in seconds. The weapon is cleared to fire a High-Explosive (HE) grenade, a training grenade as well as crowd-controlling measures such as tear gas rounds and white phosphorous types. This provides the standard infantryman (or riot police) the tactical flexibility to address the situation with the proper projectile type. When paired with an assault rifle, the infantryman can now engage targets through several options.
The AG36 is designed as a universal 40mm grenade-launching solution and is not limited in its installation on the German G36 assault rifle. The AG36 can therefore be mounted on several major current-generation assault rifle weapons including the British L85 series, the American M16 and similar-class weapons. The grenade launcher has since been developed into several variants of note beyond its original German Army form. This includes the AG-C/EGLM ("Enhanced Grenade Launching Module") which is the L17A1 in the British Army. It has also been accepted into service with the United States Army as the M320, replacing the aged M203 series. The AG-NL is a version developed for Canadian Diemaco C7/C8 assault rifle/carbine systems which themselves are based on the American M16/M4 rifles/carbines. The British Army designates their AG36s as the L123A2 when paired with their L85A2 bullpup assault rifles.