No limit on calibers short or long with same action, but the bolthead is changed out for different size case heads. A standard bolt head would shoot your 243, 25-06, 6,5 270, 30-06, 9,3 etc size cases. For magnum caliber group have to switch out to a magnum bolthead.
Here's a caliber group overview:
http://www.blaser.de/fileadmin/edito...ion_R93_EN.pdf