[QUOTE=browningautorifleicon;457667]Here's something written in a local hunting forum... Thing is, your bore is big enough to take them. I'd be with you...and try them.
Sounds like before you had .318 diameter bullets and they were barely engaging.

Both vintage military and sporterized versions of the Mauser Model 1898 bolt action rifle are still readily available on the used gun market but, it should be noted that older versions of these rifles are designed to fire a .318 caliber bullet and these rifles are designated as having “J” bores whereas, newer versions of these rifles are designed to fire a .323 caliber bullet and these rifles are designated as having “S” bores.
American

A lot of incorrect information here. The Germanicon military NEVER used a .318 groove bore size . The German military never called any bore size J or S . The actual bore size on any German military rifle from 1890 1/2 was .311 with a groove size of .321 until 1896 1/2 when it was changed to .323 + , called the Z bore change by the German military . The bore size of .311 was always right on but the groove size could [ and did ] vary from .323 up to .326 . They did not care about the groove size as long as it was above .323 . The S BULLET was made at .321 with a .323 skirt so it could work in all rifles , .321 and .323 . It had a open flat base to let it expand to seal with the larger groove rifles . So for modern shooting with modern bullets a flat base bullet or a larger dia boat tail is needed for accurate shooting . The land dia is more important than the groove to get a good bite on the bullet , so a long round nose [ lots of bearing surface to stay straight in the bore ] .323 bullet with a flat base will solve most .325 + groove barrel problems .