RE: Grizzly Bears
They weigh 80 grains each. Individually they won't penetrate as far but together they penetrate like a large slug, and that's where the damage comes in. Sort of like how the old timers would put wax in their birdshotshells to make primative slugs. Now of course the little birdshot pellets on their own won't do much damage, but when they are held together they are more or less as fragnible solid object.
And yes Iw ill have backups, most big game hunters do, espessily if they wish to do it the way I am going to.
From Squirrel to Elephant, the Shotgun is your gun.