Silhouette of the German made HK 91 rifle in .308/7.62x51 cartridge. A roller-delayed blowback rifle developed by former Mauser engineers Vorgrimmler, Löffler and Kunert, modified by Centro de Estudios Técnicos de Materiales Especiales, Rheinmetall, and Heckler & Koch. The rifle was later to be ceded rights and produced by Heckler & Koch in Germany.