when faced with a prolem/question like this call Brownell's. They can probably answer and may even have what you need. I was faced with same question on 98 Mauser's, thought it would be m/m, lo and behold it is 1/4 20. Every other thread on those guns are m/m! Also Brownells 'Encyclopedia of Modern Firearms' is loaded with this kind of info, altho seems to just cover civilain rifles and pistols, some military shotguns.