I've read enough stories in the past twenty years on the internet about people being charged by grizzlies or huge, Alaskan brown bears that quickness in getting a weapon out is of the essence.
I remember reading some years ago about one hunter who was in a group of four hunters around Yellowstone literally out for bear. They all had high-powered rifles. One hunter was killed by a grizzly because he didn't have his rifle ready to shoot a grizzly that charged him out of the brush and killed him. I can't remember if the other hunters managed to shoot the bear.
After reading that I surmised that having a powerful enough weapon which the wearer could readily fire at a fast-charging bear was a great idea. I don't particularly want to find out whether a rifle or a hand gun would be a better weapon against a charging bear when speed of drawing a gun out and accuracy are of highest importance.
Without a doubt, the rifle is the thing to have. There is so much more power in that carbine than in a handgun, that it's a matter of an order of magnitude. The reason I would certainly get one off from the rifle, is because I am usually carrying it at the ready. And hopefully, I will get all seven out of that rifle before I have to go to the pistol.
You've heard the expression that a .22 is better than nothing? The pistol is just like that. I'd much rather have the pistol than what's next, which is knife and hawk. But never think the pistol is the better option until it is.
Note that the one time I actually needed to drop a bear, I didn't have my 30/30 (which I carried at the time), and the .45 ACP I had on me stove-piped. I threw the gun at him, ditched my pack, and swarmed up the nearest tree... Had he not stopped to investigate the pack, I would not be here writing this right now.
But yes, a charge is frightfully fast, and usually under fifty yards. That may sound like a ways, but a bear at full tilt covers that in seconds... Considering that the first shot is normally at the ground along side him to scare him away, if he means it, you really don't have any time.
But it really ain't just griz. Moose, in my mind, are more of a menace. Other than being between a sow and her cubs, most of the time, you can turn a bear, or he is false-charging. If a moose gets it in his head that he don't like you, he will not stop... And you really never know why they get mad at you... they just do. And rutting deer can get pissy too.