European 8x57 ammo is loaded to standard pressure, while US-made ammo is loaded to lower pressure in deference to the older, smaller-diameter bore of the original 8mm Model 98. It should be fine in your 1943 Model 98. The only real exception might be in a European-made 98 sporter chambered in 8x57. For some reason, the smaller .321 bore remained popular in European sporters decades after the military had gone to .323. If you ever pick up a European commercial or custom sporter in 8x57, it would be wise to slug the bore before shooting it, just on the off chance you've got one of these smaller bores, especiallly if based on the 88, 93, or 95 actions, as some are.