I am reminded of my hunter safety class when I was a lad;
The instructor took a large head of cabbage and placed it on a post 20 feet from us. He informed us that it was significantly tougher than a human skull.
One shot of a 12 ga Mag goose load of BB shot and it was destroyed like the watermelons in the video. Our 12 year old eyes went WIDE with newfound respect for ' bird shot ' LOL
Take a look a the size chart:
http://www.wilsonprecision.com/shotinfo.html
B and BB shot is no where near what is commonly thought of as ' bird ' shot like number 6, 7 or 8.
I would not feel undergunned with a mag load of B or BB shot.