I'd rather fill my tent with bear spray(which has been proven more effective than a gun) than have my tent turned into toilet paper by the bear after he reduces me to bear poop.
It has not proven more effective than a gun. There have been a number of studies about bear spray effectiveness, but I suspect the results depend on who is paying for the study (traditionally). Also it is very dependent on environmental circumstances, including wind. Even when the circumstances are perfect, it's still hit or miss. Guns are hit or miss as well -- you hit or you miss, but when you hit, I personally like my chances better than relying on what amounts to a condiment. Sorry, but in a tent (or outside) I'm going to rely on one of my .50 caliber handguns to get the job done. JMHO.
