FN CAL
The CAL ("Carabine Automatique Légère") was a Belgian weapon manufactured by Fabrique Nationale. It was the first 5.56 mm rifle produced by the Fabrique Nationale. It resembled the company's highly successful FN FAL, but was an original design. Unlike the FAL, it was a market failure, although its development led to the reasonably successful FN FNC. Design details. Prior to the development of the CAL, FN had already constructed a scaled-down FAL prototype before shelving the idea as unmarketable. Noting the growing sales success of the cheaper and simpler HK G3 rifle, FN decided that for  any future rifle to be competitive in the marketplace, it would need to use fewer expensive precision-machined parts. These would be replaced by less expensive castings and stampings where possible. While the construction of the new CAL reflected these design principles, it was still relatively expensive and complex, and met with no significant sales. It was eventually dropped for the even less expensive FN FNC. A small number of FN CALs were sold to the civilian market in the US. Operation. Although the weapon resembled a scaled-down FN FAL, it in fact used a rotating bolt, unlike the  FAL, which used a tilting bolt design. The earlier models of the CAL had a three-round selector system, which allowed the weapon to fire a three-round burst with each trigger pull. The CAL could also fire in fully and semi-automatic modes. The gun used long stroke gas piston to operate the bolt carrier, and the bolt itself had interrupted lugs to lock it into the chamber. Locking lugs were cut diagonally at a steep angle. So while the bolt is rotating to unlock, bolt face is slowly moving back, giving primary extraction of the case. Similar feature  can be seen on MG-30, MG-15, MG-17 and MG-34.