Standard length Actions are long, and are used for all standard length + rounds (30-06 family, Win Mag and H&H family),
... so the mag opening will eat anything you care to feed to it...within reason...
They even made 'large' ring magnums (currently only large ring short mags yuck
), which would be ideal for a RUM (in fact were chambered in RUM) - but these are scarce, if at all available in Aus...and offer probably more psychological advantage over standard ring when using up to Magnum diameter rounds.
Why sav? theyre the DIY shooters best friend, whip off the barrel nut, the old barrel and screw on a new barrel.
Headspacing is a matter of throwing in the gauge and screwing in the reamed barrel, thats why pretty much every US manufacturer has adopted the Savage barrel nut system...
Its not too difficult to have a rifle with multiple barrels, if you want