I learned a long time ago when one is fooling with an older, say WWI or earlier, European firearm you better slug the bore and cast the chamber. I have a couple 9.3's that are more 9mm than 9.3. I shoot .358's in them. A few rifles that were sold to me as one cartridge turned out to be something completely different but that's more a reflection on the seller than the rifle. However, it showed me the wisdom of casting the chamber and slugging the bore. My Strover Mauser from about 1919-20, supposedly well into the .323 era, still has a .318 groove diameter. Not an uncommon occurrence for "between the wars" sporting rifles until one gets closer to WWII proof dates. Even then, a fella better check. Of course that's a good part of the reason I like to fool with those old rifles. Figuring out what they are, learning about them, working up cases and loads and putting them back to use. Makes for some interesting conversations among the "tacti-cool" and non-handloading crowd. The questions I get then are , "how did you do that", or "how did you know" and most often...and for a dedicated and thoroughly committed handloader probably the most amusing, "can you buy ammo for that"? I can't buy ammo for probably half the rifles I own!
