ibschmidty,
I carry an extra magazine (5-rounds) on my rifle, my Glock 20 (10mm with 16 rounds of 180 grain HP and extra magazine of 15 rounds) and a big knife, when hunting in Arizona. If I am hunting in the southern part of the state, I also carry a few magazines of SS109 or Hornady TAP(30 rounds each) in my pack for 2-legged predators(self-defense), just in case. Those 2-legged pradators sometimes have AK-47s (I have not seen any yet, though).
I do not have the AZ Game & Fish book handy to investigate the high-capacity magazine rule for rim-fire firearms, so will have to defer to someone else on that point.
I bet you have some big cats in Utah.
Karl in Phoenix.