Development began around 1967 when NATO launched the idea of adopting a second standard small-caliber ammunition. Three competitors were then nominated: one American, another Belgian, and finally the German Heckler & Koch. NATO quickly lost interest in caseless ammunition but the West German Government held on. During 1968–1969, the government of West Germany started a feasibility study into a future assault rifle and three contracts were awarded respectively to Diehl, IWKA Mauser and Heckler & Koch. The terms of reference (specifications) were very general, calling for an improved infantry weapon with a better hit
probability than any then in existence, yet fulfilling the
FINABEL range and rate of fire characteristics. The designers were given a free hand for the methods used, but Heckler & Koch, attempting to obtain improvement, approached the design with radical change in mind. From the very beginning, it was obvious the required hit probability could not be achieved with common
iron sights. An optical sight was H&K's solution. The Hensoldt AG, having delivered 100,000 optical sights for the G3, cooperated with H&K on developing a small sight with low power magnification which would allow target acquisition with both eyes. However, it was dropped because of the cost. The weapon was to be short, but only 37 cm would have been left for a
sightline, too short for a common iron sight. In mid 1968, Hensoldt presented an affordable
reflector sight. It was based on an old and nearly forgotten patent, and a modernized model had to be built by a master from the assembly department. On September 30, 1968, Hensoldt was commissioned for a study for further development. Numerous studies followed in the period between 1970 and 1971. Intensive tests were run by Heckler & Koch and Dynamit Nobel in search of a suitable ammunition. The early sideways ignition design gave way to a tail ignition design. By 1970, studies progressed far enough to allow the construction of an automatic single- and 3-shot burst model but without full-automatic operation. Sometime in 1970, the box magazine was selected. To study the dispersion, a model firing 9×19mm and equipped with the reflexive sight was used. It had a cadence of 2400
rpm. The study supposedly was conducted by a research institute of the
Fraunhofer Society (Fraunhofer-Gesellschaft). To determine the precision, a laser was used, fired onto a film during the 3-shot burst. The
free-floating barrel design was found to contribute significantly to the precision of the weapon. At the end of September/beginning October 1971, the weapon was fully completed with full automatic fire and chambered for 4.9 mm and fed from the side. In early 1976, doubt about the viability of the reflex sight rose. The contrast requirements in adverse condition and added features like variable brightness and distance settings drove cost up, exceeding that of a proper scope of similar size. On June 11, 1976, it was decided to switch to a scope. On June 15, 1976, the specification for a scope was finalized and the first model presented on August 5/6, 1976. In November 1977, the FODTP changed the specification accordingly. At the end of the contract in the summer of 1978, it was found to satisfy the requirement. Meanwhile, the caliber was changed to 4.75 mm with
Prototype 3.
Prototype 4 and
Prototype 5 equipped with the scope took part in the preliminary NATO field test in 1977 in
Meppen. After the contract with the FODTP ended H&K, Dynamit Nobel and Hensoldt were forced to continue development on their own with their private funds. On 28 October 1980, NATO approved the standardization (
STANAG 4172) of
5.56×45mm NATO as the second small caliber cartridge for use within the alliance. . Up to 1982, changes were made following the test. The caliber changed to 4.7×21mm for
Prototype 6. The conventional nitro-cellulose propellant was replaced by High Ignition Temperatures Propellant (HITP) based on
Octogen. The barrel received
polygonal rifling. with the U.S. Department of Defense and for the adoption of caseless ammunition with the Bundeswehr and NATO. On December 8, 1986, Hensoldt was ready to deliver the final "Zieloptik ZO 1". The G11 K1 (K for Konfiguration) production model was completed in March 1987. Field test and troop trials began in June with the
Bundeswehr in
Hammelburg and lasted until January 1989. It achieved a 100% higher
Ph than the G3. The final development of the ammunition was completed toward the end of 1988 with the same dimensions as 4 years earlier. In March 1989, the first
Operator´s Manual was made for the G11 K1 for the ACR evaluation. By then, work had already started on the G11 K2. On March 3, 1989, the first five ACR units were shipped to the Aberdeen Proving Ground. In May, H&K began to instruct the testers on how to operate the weapon. The volume of a contract for the Bundeswehr alone was to cover 300,000 units worth 2.7 billion DM. On April 1, 1990, the
Warsaw Pact dissolved, leaving West Germany with a surplus of hundreds of thousands of Kalashnikovs. The development of the G11 from 1974 to 1989 had cost the tax payer 84.1 million DM, while leaving H&K with a debt of 180 million DM. H&K was permitted by the
Federal Office of Economics and Export Control (
Bundesamt für Wirtschaft und Ausfuhrkontrolle) to export the rifle to 80 countries, and give licenses to 15 countries. In the 28-month-long Phase II, the G11 caseless ammunition was replicated and customized to U.S. Army preferences (higher burn rate). In May 2007, the caseless ammunition was scaled and adapted to the 5.56 mm projectile in a telescoped and round form. An alternative
polymer cased version was created in parallel. ==Design details==