After watching hunters kill Brown Bears in Russia with a SKS in 7.62X39. I would say a 30/30 could probably kill everything on planet earth if you put the bullet in the right place.
Yeah great....but would you really want to?
I'd quit hunting first....
Who'd hunt the world with
that? 
I wouldn't want to. And I've taken a moose with the 30-30.
No problem with either. Carried 30-30 where the grizz roam for years in AK... never felt the need to say I was not safe. Could and did carry bigger at times, and do currently, but nothing huge...
SKS are some great rifles, generally a better choice than an AK, a decent round power wise, and with good bullets and accuracy, you can do a LOT with the round.
Hell I kill stuff out to 200 all the time with a 300/221 subsonic 194s.... only running around 1000 fps...
