Originally Posted by
AndyB1
The early 98 Mausers were .318 groove diameter. When converted to the .323 design all they did was cut the grooves deeper, so the bore diameter was not changed.
The only 98 Mausers from Amberg were 8x57.
A chamber/throat cast w/cerrosafe (Brownells) would tell you what you have.
As I recall from the Collector Grade books on Mausers, the bore diameter of both the J (really I) and S bore guns was the same. Only the groove diameter varied. (?) Frequently writers are sloppy about "bore diameter" when what they mean is groove diameter. If an "S bore" rifle really had a .323 bore, a .323 bullet would rattle down it. It has .323 grooves as we "lead shooters" know that when a bore is slugged and you measure the slug, you are measuring the dimension across the bottom of the grooves.
I once owned a fancy German inter-war sporter in 8x60 that had .318 grooves while the ammo was .323. Theory was it increased pressure, hence performance. With 232 gr H Mantle bullets it kicked the snot out of you.
The 8X60 came about to be able to use all the WW I 98s w/o breaking the treaty rules of WW I.
Many that came here became 8x63 (or so) know as the 8mm-06, a serious thumper.