Ammo, I see hunting ammo made by a Serbian group called 'Partisan' being sold at gun shows or you can load your own, Huntington's of California has dies and new brass ( http://www.huntingtons.com/cases_graf.html ), the K31 caliber is called 7.5x55 for some reason despite the K31 being basically a 308 caliber rifle.
Again the overall cartridge length given in books is for that Swiss fmj bullet and is about a whole quarter inch wrong for normal 308 hunting bullets. You can load those Graf cases with ordinary Sierra or whatever 308 168gr hunting bullets but you simply walk the die in a turn or two at a time until you get a cartridge that the bolt closes over easily, and that's your real cartridge length.
If ya ever get bored enough to do the math, 7.5 mm is .308 inches. 7.62 mm is .311 inches, a common bore diameter for the commies. Don't know why NATO uses 7.62 as a designation for .308 bullets.