Winchester 8x57 brass case heads run a little small, so they'll fit after resizing in 8x56 die and trimming. Winchester was scarce for a while, so I picked up Hornady 8x57, and it was small enough to fit after resizing and trimming also. Finally, I have read that the PPU/Privi brass will fit. Remington didn't fit.

BTW, my bore was .327 vs .323. My measurement across lands was fairly tight, like .314'ish, so plenty of rifling engagement with .323 bullets. I bought a .329 mold to see if I could make the rifle more accurate and haven't cast with it yet, but 175gr .323 Sierra's shoot okay with 3031 and 4064 and RL15. 44g RL 15 is best so far with the 175g Sierras.

HTH