The Heckler & Koch G11 is a non-production prototype assault rifle developed from the late 1960s to the 1980s by Gesellschaft für Hülsenlose Gewehrsysteme (GSHG) (German for "Association for Caseless Rifle Systems"), a conglomeration of companies headed by firearm manufacturer Heckler & Koch (mechanical engineering and weapon design), Dynamit Nobel (propellant composition and projectile design), and Hensoldt Wetzlar (target identification and optic systems).

Although the weapon was a technical success, it never entered full production due to the political changes of German reunification and lack of procurement contract.

[5] 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 (named after France, Italy, Netherlands, Allemagne, Belgium and Luxembourg) range and rate of fire characteristics.

The designers were given a free hand for the methods used, but Heckler & Koch realized that the only way to obtain any significant improvement was to radically change the approach.

Intensive tests were run by Heckler & Koch and Dynamit Nobel in search of a suitable ammunition.

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.

[7] In January 1973, the defense ministries of West Germany and Great Britain agreed on exchanging information on development of infantry weaponry and ammunition.

Together with the Federal Office of Defense Technology and Procurement (FODTP)(Bundesamt für Wehrtechnik und Beschaffung),H&K's rotating breech was selected for further study and development.

In early November 1973, at a NATO workshop conference in Brussels, West Germany was appointed to develop the second generation (rifleman) rifle.

NATO-wide testing began in 1977 with the goal of having a second smaller caliber weapon alongside the 7.62×51mm NATO round rifle.

West Germany wanted to have it ready by then, but the caliber was changed to 4.3 mm, delaying prototype development by months.

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.

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.

[7] In 1978, Mauser competed with their own weapon chambered for caliber 4.7 mm in a conventional case design but ultimately lost to the H&K G11.

In 1984, the Gesellschaft für hülsenlose Gewehrsysteme (GHGS), founded by H&K GmbH and Dynamit Nobel AG, completed a license agreement for a custom version (worth US$3.8 million)[12] with the U.S. Department of Defense and for the adoption of caseless ammunition with the Bundeswehr and NATO.

At the same time, the Cabinet of Germany confirmed questions by the Bundestag about the signing of a contract in early 1990 for the adoption of the G11 and that it is part the budget (Haushalt 1990 EPL 14).

[16] On April 1, 1990, the Warsaw Pact dissolved, leaving West Germany with a surplus of hundreds of thousands of Kalashnikovs.

[17] In the 28-month-long Phase II, the G11 caseless ammunition was replicated and customized to U.S. Army preferences (higher burn rate).

[14](See terminal ballistics) The design principle was to increase target hit probability by firing high rate multi-round bursts (salvos).

Tests have been run using a prototype shotgun test-bed called CAWS to see whether a single-shot, multi-projectile system could achieve the range and hit probability requirements.

The rifle was designed to have a dispersion such that a man-target running at a speed of 6 km/h at a distance of 250 m would be hit even if the lead angle error (2 mil) was off by 51 cm.

Even though the rotary chamber does not lock up in the true sense of the word, the fact that it has to rotate in and out of alignment with the barrel means that the G11 can be considered to have a lock/unlock phase.

The number of hours of maintenance required for the G11 compared to other designs is not clear, especially since the effect of the powder used in the caseless ammo remains unknown.

Designers claimed that, because there was no ejection cycle, the internal mechanisms would have little chance to get exposed to external dust, dirt and sand, which would supposedly reduce the need for cleaning.

Premature ignition of ammunition from heat in the chamber, known as cook-off, was a major problem with early prototypes of the G11 where synthetically bound nitrocellulose, formed into blocks, was used.

Normally, when a cartridge is fed into a chamber, its case insulates the propellant from igniting until its impact-sensitive primer is struck by a firing pin or striker.

To solve this, Heckler and Koch formed a partnership with Dynamit Nobel, which redesigned the cartridge to use a new high ignition temperature propellant (HITP).

This would increase the maximum rate and duration a gun could fire before cooking off rounds, but the VEC-91 never took advantage of this, since it was a bolt-action rifle.

[14] In line with another NATO requirement for a personal defense weapon (PDW), a handgun concept, Nahbereichswaffe (NBW),was created.