Actually, and you need to check it for yourself before taking my word for it, American factory loaded 8x57 ammo is loaded with a compromise bullet that'll work in either the J (.318) or S (.323) bores. It's also loaded to pretty anemic performance levels out of deference to weaker non-M98 actions.
I know it was done "back in the day", I don't know for a fact that it is still the case, or if it was done by all manufacturers.
Last edited by gnoahhh; 02/12/10.