My understanding was that even though the 6.5x55 nominally runs a .480" case head, most current brass is slightly undersized (while most of the bolt faces are slightly oversized)….basically, it should run fine in a standard .473" cartridge bolt. I'll check mine with a few cases just to be sure.

260, do you recommend using a barrel wrench or just a simple barrel vise? I have some barrel vise inserts I can use with a large vise, but no action wrench. I don't mind buying one, but not sure I want to buy one just for this project...although, if it works out well, I may look for a short action XS7 to build a .250-3000 on.