There are video's on the net (you tube) of bears charging people. And the person stopping the charge cold with a shot into the air.
http://www.bing.com/videos/search?q=...B42&FORM=VIRE3
http://www.bing.com/videos/search?q=...ED&FORM=VRDGAR
I imagine a shotgun even without slugs ( Aka turkey gun) can do the same
edit add to answer your question
The particular outfitter I used has a "lead guide". They bring you to your stand, the first night to show where the stand is..after that they don't enter the bush...no need to chance extra people/sounds/smells...........and pick you up on the road later at night...
The spring I hunt I did back this past May, pickup was around 10:30pm. A couple nights it meant standing in the bush in the dark a long time waiting for them to pick us up.
You get used to it.
The "take away" here is to reassure you. Thousands of people hunt bears with bows and have for years. How many people in Ontario have been mauled by black bears? Very, Very, Very few