The 8x60 S Magnum was a high-pressure cartridge and rifles chambered for it were especially proofed for the higher pressure. Ammunition for the rimmed version have the same straight knurling as proof cartridges to provide a tactile identification. I don't have any of the rimless version so I'm not sure if it is treated the same way. The 8x60 S was created after the Versailles Treaty to provide a way to rechamber 8x57 IS hunting rifles for a non-military cartridge, thereby keeping them legal. The 8x60 was created to provide a similar rechambering for 8x57I rifles as well. Rimmed versions (8x60 RS and 8x60 R) were loaded also and the 8x60 RS Magnum came along later, providing greatly increased ballistics when compared to the others. I believe commercial ammo for the 8x60 S is available from Graf's.
Mike
