RE: least powerful cartridge
But see your definition of be " undergunned" is your definition (i.e. opinion). Some might think your 308 is undergunned, and the reason you lost your animals was you were undergunned and if you shot them with a gun like 338RUM, they would have dropped in their tracks.
See what I am saying. I mean you don' t get any brownie points by shooting deer with a 308Win over a 300 Weatherby.