I haven't run into any duds in my 22lr history. I can empty a 10 round clip from my Walther P22 in 2 or 3 seconds. That has a little stopping power I would think...however in the interest of full disclosure I do carry a 38 special. If 32 ammo were readily available I would carry a 32 revolver with HP
On the brown bear...I hope I can out run one of the folks with me. If the bear were attacking my tent it is probably already too late unless I am sleeping with my 30 30 at the ready.
If the bear climbs up the tree after you it is a black bear...if the bear shakes the tree until you fall out it is a brown bear!