I hope I don't anger anyone here on LONG Range Hunting by mentioning a slow moving, fairly short range round.
I hunted black bears about 400 miles north of Montreal a couple of years ago. I took a 45/70 guide gun shooting 350g Corbons and 2 buddies of mine each took 300 Win Mags. Can't remember their bullet weights or brand but I do recall thinking that the bullets were, in my opinion, lightweight. I fired one round at a bear from about 40 yards and dropped it. Aimed exactly at the shoulder. My buddies on the other hand, at the same ranges, fired 2 - 3 rounds to kill their bears.
Guys have killed cape buffalo with 45/70s GGs in Africa. Although I wasn't shooting the 560g rounds African hunters were, I didn't feel undergunned in Canada. I should say that my first two rounds in my GG were 350s the third was a 405g flat point penetrator and the fourth round was a 460g corbon hardcast. the 460g round was for me in case the bear was mean and tough enough to get through the first 3 hits.
I had a firearms instructor from Arizona once say in a class that the mass of a bullet, along with good shot placement, is what neutralizes an attacker. At least in shooting a bear, I'd have to agree with his assessment.