I have recently sold my 8x58R Rolling block but I can tell you what I shot with some success at Bisley historic arms meetings. My original cases were supplied by the now extinct North Devon Firearms but these were turned cases and were only suitable for Black Powder loads. I then discovered that it was possible to make the cases from 348 win brass and these are suitable for smokeless loads. I used Accurate 5744 with loads upto 22gns behind a 240 gn bullet which I cast from an NEI mould.The bullet casts at around .330 and I sized and lubed it to .329. That tied in well with NDFS's guide which suggests the bore for these is .328 - .329. This bullet is gas checked ( unless you need to conform with MLAGB regs using black powder) and the velocity was about 1700fps. Because there is a lot of space in the case with that load I used a tube of sponge which I punched from 1" thick sponge block to keep the powder pressed to the case base. If you need to find the mould goto
www.neihandtools.com/catalog.htm and click on page 6 and look for .330 - 245 #98. I hope you find this useful.
Regards, Ian.