I don't know about Canada, but in the US the .30-06 is far more available, which would bump it up for a "just one gun" caliber.
And yeah, you can load a .30-06 down. 140 grain .30 caliber bullets don't have the best ballistic coefficient, but they'll work just fine within 300 or so yards. You can also back off the powder charge and get the velocities down to .308 levels for even more recoil reduction.
Last edited by Regolith; September 20, 2012 at 05:13 AM.