Steve -
The .223WSSM is a round in the .220 Swift class of velocity/bullet weights. It will literally blow foxs into 2 pieces, just as a Swift will, with many loads.
: There is no comparrison on small fur bearers. Better for fox, is a CZ .17Rem with factory 25gr. Hornady HP's.
: Inside 300yds. even the .223 is a bit rough on hides.
: Darn good price on the Browning, though - but .223-town, it isn't. Brass is expensive and so is the ammo. .223 ammo is cheap in comparrison and fully capable of ripping up a fox with it's 800fps lower velocity.
: If you want some small-bore shooters opinions, go to www.saubier.com and ask this same question.