I don't want to make Raimey have a heart attack, but you don't need a chamber cast when there are two choices of chambering. A hand loader usually has a dial or electronic caliper, and it can be used. Measure the chamber diameter just ahead of the rim recess. If it is 8x57R/360, it will measure around .427"; and if 8x57IR,around .465". There is enough difference to be pretty clear. I vote for 8x57IR due to the 8-88 mark. If you fire a cartridge in the drilling and don't size the case, what ever bullet diameter that will easily fit into the case can be used in loading for it. For sure you can use .318", it is pretty likely use .321" and possible for .323". You can easily make .318" bullets from .321" or .323" or in between. If you don't have a caliper, you can tell the 8x57IR from 8x57R/360 by comparing the chamber to a 30-30 case and 30-06 case.
Mike
