Well, that's a whole other issue. And, I have a .45-70 rifle, (three) a .350 Remington Magnum, heck a .75 caliber musket and .62 Caliber rifle, real bear whackers.!!! Those are "best" for me, for sure, but sometimes I like to travel light. I play the odds, and I think that even a .30-30, at ten yards, (or closer) will put a bullet (a good heavy stout one) into Mr. Grizz's brain, or do pretty good damage into the vitals. If I miss, well then...serves me right!!
However, when you have a frontal shot at close range, as when a bear or cougar is coming at you, the bullet has the potential to reach more vitals, or it's brain, I think, than if you zinged one through the rib-cage or just the lungs shooting from the side. I may be absolutely wrong there, but again, I'll take my chances. I feel as comfortable with the .30-30 as I do with my .44 mag pistol, and most think a .44mag is bear repellent, but I believe the thutty thutty from a rifle produces a bit more smack down than the .44 pistol. (sometimes I take a .22 rifle and just the .44mag pistol)(or my bow and arrow)
Or..!!!...in other words, when I go deep into the mountains and into Grizz's back yard, I'm willing to travel light and leave the big heavy guns at home, and take my chances. After riding motorcycles all my life, I know about taking chances!
Dang, that was sure a lot of hot air!