Harry,
Yikes! That is a fairly astonishing set of numbers. I thought everything but the Weatherby's and the Van Horn rounds were .220 off the belt. But -.008 for the brass?!! My first thought is that a bottle-neck case will end up headspacing off the shoulder before the belt touches down. Maybe you should chamber it that way on purpose as insurance if the manufacturers are that loose?
Second thought: since the Savage headspace is so readily adjustable, maybe you're better off buying all the brass you're likely to use in it at once, from the same lot. Then set the gun up for that lot. What a nuisance. An not knowing if a commercial cartridge would be able to chamber afterward is unsettling. Can you carve a hollow in th butstock to carry the nut wrench with you?
Nick