Larry,
Thanks for sharing the link. I'll re-post it because it has valuable info.
http://www.fws.gov/mountain-prairie/species/mammals/grizzly/bear%20spray.pdf
Disclaimer: it's not my intent or interest to convert or change anyone's mind.
Knowing which tool to deploy (gun versus spray) will be 100% effective at the right moment, is tough to predict, considering adrenalin, marksmanship, duration to neutralize threat, wind, proximity, visibility, sleep level, element of surprise.
There is no single strategy that will accommodate all scenarios.
In case of a stalking bear, the human would ideally have enough time to unpack the pepper spray and be ready to deploy when the bear charges, 25 ft away, and 6 secs lead time.
http://wdfw.wa.gov/living/files/BearSpray_SafetyforPeople_SafetyforBears.pdf
• Suggested bear spray duration of 6 seconds to deal with a variety of charging scenarios and to adjust for wind.
• Suggested bear spray distance of 25 feet to allow a charging bear to meet the expanding cloud far enough away as possible. This gives the bear time to feel the effects and divert its charge.
The one time I surprised a bear while he was eating sunblock lotion from inside someone's claw-shredded tent, he charged at me and my dog, I got my puppy to sit, I stepped in front on my dog, I raised both of my poles in a crossed X-shape, then I yelled out my loud impersonation of a GROWWWWWWL. The running bear changed direction and leaped onto a tree with agility like a spider monkey.
In case of a person sleeping inside a tent, suddenly awakened by external heavy breathing, then the 6 secs of pepper spray at 25 ft distance is not applicable. What I have done in the past, is yell out "Who's out there?" and "Go away bear!" most of the time it was probably a squirrel, coyote or deer. I listen for the running away animal sound to guess it's weight.
When the animal is persistent, and sniffing around the tent wall, I've tried fist-punching the tent wall may be I get lucky and startle the animal.
I've never had an animal claw its way inside my tent, however pepper spray as defense inside the tent is not the right tool.
Presumably, if you have the misfortune of physical attack and fighting for your life, some say to play dead and take the LAPD beating, then others say that point blank defense with anything nalgene or trek pole, tent stake, knife, stone or brass projectile delivery system.
The scenario we all want to avoid is fear overcoming a startled sleepy camper that fires randomly at shadows.