Nope, none of the previous suggestions here are what the OP needs. The modern bore & bullet diameter, indicated by the "s" in the caliber designation means .323" bullet diameter. And the Rimmed cartridge is designated but the "R" . The OP needs the old .318" diameter bullet ammo. 8x57IR - and S&B, or RWS are the only two manufacturers that I know of that still make it. ( the I and the J are interchangeable in German script)
There are actually four different CIP spec cartridges, two with .323" diameter bullets, 8x57IS, 8x57IRS, and two with .318" diameter bullets - 8x57I, 8x57IR. And for USA manufacturers, SAAMI has the bastard 8x57 "Mauser" which is the rimless case loaded to low pressure with an in-between size bullet so it won't blow up 8x57I rifles when shot in an undersized bore.
When I had a drilling in 8x57IR, I got some RWS ammo off the shelf at Italian Sporting Goods in BC.