...While it is true that the little 7.62X39 ,because of it's spitzer bullets can match the 30/30 energy's and trajectory,it can not match the quality of bullet construction in the mass of available loadings. Even in the best of today's available loadings the sectional density of the common projectiles used in these two rounds augers in favor of the 30/30 . Most 7.62X39 rounds feature 123 grain bullets, the 30/30 150's and even better 170 grain bullets. Cor-Bon makes available a 'souped up' 150 grain loading available for the 7.62X39 but it is not easily found by most ammo buyers, and it's pressure levels are hard on auto loaders. I have a CZ 527 carbine in 7.62X39, which with high quality 123 grain softpoint loadings by S&B, I use on an occasional deer hunt. It has performed well for me, and is a joy to carry and extremely accurate. The little CZ 527, a mini-Mauser bolt design,can safely use ammo rolled up with 10,000psi more pressure than the SKS or AK want to live with (50-55000psi, while 40-45K is the safe max the auto loaders deal with). Such loads are a hand loading only for now , but do take the little Russian round up a notch for bear..
......Hey a 22RF will kill a bear, but common sense chooses not on what "can kill", but on what kills quickly with a margin of safety for the hunter. It has long ago been found that it is better to nibble on bear hams, than for the bear to nibble on yours!