In 1991 the Izhmash factory in the city of Izhevsk began full-scale production of a modernized variant of the AK-74—the AK-74M (M—Russian: Модернизированный; Modernizirovanniy or "modernized") assault rifle that offers more versatility compared with its predecessor. Apart from several minor improvements, such as a lightened bolt and carrier assembly to reduce the impulse of the gas piston and bolt carrier during firing, the rifle features a new glass-filled polyamide stock that retains the shape of the original AK-74 fixed laminated wood stock, but side-folds to the left like the skeletonized AKS-74 buttstock. Additionally the AK-74M features an improved muzzle device, a reinforced smooth dust cover and a redesigned guide rod return spring retainer that allows firing the GP-25, GP-30 and GP-34 underslung grenade launchers without having to use the previously necessary additional receiver cover fastener. Each AK-74M is fitted with a side-rail bracket for mounting optics. The AK-74M would have been adopted by the Soviet Union as the standard service rifle, and has been accepted as the new service rifle of the Russian Federation.