Just make sure of it is a 8x57J or an 8x57JS. The JS is slightly larger in diameter. If it is an old surplus rifle there is a small chance that it is a J. As in all oldies there could be wear and tear that means that the rifle cannot handle hot loads. Most manufacturers make .323 cal bullets. Nosler, barnes, norma, hornady...

Norma has factory ammo including cheap trainers. (maybe not in US).

The caliber will work for anything a 30-06 will work for.