The FR-8 is a Spanish rifle manufactured in the 1950s as part of Spain's adoption of the CETME semiautomatic rifles. Spain was not only moving to their first semiauto rifle, but also changing from 8mm Mauser to the new 7.62mm NATO. It was not possible to immediately equip everybody with the new rifles, so a parallel program was instituted to modify the now-obsolescent bolt action rifle in inventory into a more useful configuration.

FR-8 was the designation for an M43 Mauser (of the model 98 pattern) rebuilt as a training and second-line rifle. The original barrel was replaced with a 7.62mm barrel , along with a front sight duplicating that of the CETME. Where the CETME had a charging handle tube above the barrel, the FR-8 had a similar hollow tube below the barrel, which was used for storing a cleaning kit. The rear sight was similarly modified to duplicate the CETME sight picture and range adjustments. A muzzle brake was fitted so that standard 22mm NATO grenades could be launched (a further benefit for training compatibility).

Contrary to popular misconception, the FR-8 was designed to be used with normal full-power 7.62 NATO ammunition, not a reduced-charge specialty round.