Brownies are getting very conditioned to equating shots with food. They hear a gun go off and they know there may be a dead animal in close proximity to that shot. I personally carry a very large caliber handgun ( .500 S&W) as does a couple of my boys when in Brownie territory. My oldest and I both have had encounters where we have had to defend against charging Browns and we were both lucky to hit our marks. BUT both of us are highly trained with handguns and practice constantly. As was pointed out, to drop a charger, you need to hit CNS by either a brain shot or spinal. Anything else will absolutely NOT stop a full on charge. I personally recommend folks to carry a short barreled (as short as legal) 12 gauge pump or semi loaded with slug, 00 Buck, slug in the magazine. Most people haven't trained like I and my boys do with handguns and just aren't as proficient with them. Imagine if you will, a bouncing tennis ball (That would be the size of your target) coming at you at around 35mph and trying to hit that with a handgun. Especially if that tennis ball is wrapped in 300-1500 pounds of angry Brown bear! People tend to sight better down a longer barrel than that of a pistol.
As far as bear spray goes, there is one seriously major flaw to that and that is WIND! If the wind is in your face, you are going incapacitate yourself not the bear! And you can bet, 9 times out of 10, if you spooked the bear it is because you were UPWIND of it! That means the wind is in your face! Major flaw to that folks.
Now, most times Browns and Blackies both are more shy of you than you are of them and will high tail it out of there before you ever knew they were around. But, as was stated, there are times when you sneak up on one and startle it into a charge. MOST times there will be a bluff charge (unless you are inbetween a sow and her cubs) and the best thing you can do is make yourself as big as possible and back away. DO NOT TURN AND RUN as that will trigger a chase reaction but back slowly away. That will usually remedy the situation and you will both go on your merry way.