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 side way 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 the Fraunhofer Society (Fraunhofer-Gesellschaft) (based in Weil am Rhein). To determine the precision a laser was used which was 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.