I pulled up the specs on the Howa 308 and with Forged, one-piece, bind-proof bolt with dual locking lugs, M-16-style extractor and large cocking indicator. They make two size extractors which are mill cut and when you open the bolt face it can be hard to mill a mag extractor to have it open enough. The bolt face for the 308 or rim size is .473 the 300WSM is .535 and you also have to change out magazine etc and may have to open feed rails. Myself I wouldn't mess with the bolt and another problem is barrel length on the 308 it's short for the mag you want something around 24". I wish I could be alittle more positive. Well good luck