While early ( 1949 -- 50 ) Soviet models had spring - loaded firing pins most variants of the SKS have a free floating firing pin within the bolt .
Spring - loaded firing pins held the pin away from cartridge primers until struck by the action 's hammer .
While early ( 1949 -- 50 ) Soviet models had spring - loaded firing pins , which held the pin away from cartridge primers until struck by the action 's hammer , most variants of the SKS have a free floating firing pin within the bolt .