Hoppdoc:

A .30R Blaser is a fairly new german creature. It's ballistically somewhere between a 30-06 and a 300Winmag.

I know of a double that has been re-chambered from .30-06 to .30R. This spesific double was a Heym (80?), it didn't regulate well at all, so the owner didn't risk any thing giving it a try. After the rechambering it actually regulated better....

A re-regulation isn't such a big deal, and well worth it if you want to get a rimmed cartride. I might shop around for a .30-o6 in near mint condition and do the same. The larger case gives meg the advantage of lower pressure. However, the factroy loads are close up to 300mag...