There should be a rule, and a sticky...
NO More F'ing bear defence threads
There should be detailed instructions on how to use the "Search" function on the site, and just regurg one of the 400 bear defence threads....
ANd do a search on buckshot and the extensive testing that has been done on it with regards to penitration.
Its useless. Inside of 10 yards its like using a varmint bullet for your rifle. Hit your target, and it fragments. your pattern with a cylinder choke should be less than 6 inches at this distance (likely closer to three), and one slug inside the same area @ 10 yards will do a hell of alot more damage than 9-30 pellets.
Spray and pray doesnt seem viable, especially when your life could be on the line.
A 12 with a slug is a formidable stopper allmost regardless of what slug you Choose.
Remingtons new buckhammers are a hell of a thump, and will push through anything you put infront of em. But than again, so will brieneke's and Winchester Xpert HP's (and a zillion other slugs all arguable as to which is best, but lethality is something no one seems to argue).
A 30-30 is as valuable in your situation as a 45-70, or a 505 gibbs. Your dealing with albeit big blackies, but none will shake off a hit or 4 from a 30-30 and eat you.
The bottom line is to choose the gun you want, and put some time in practicing the type of shooting you expect.