Mauser Question

by Art , Littleton, Colorado, Monday, September 24, 2012, 15:58 (4445 days ago)

Friend of mine has had his grandfathers 8MM Mauser for the past 50 years. His grandfather was in the Italian Army I believe prior to WW ll. He came to the U.S. way back. Any way my friend asked me about some markings inside of the receiver. When the bolt is opened he can see the marking 9.1 and either NN or NM (kind of worn) on the off side ejection opening. I know this is very little infomation but does anyone know what this designates? My friend lives in upstate New York so I can't examine this rifle my self.

Thanks
Art