Take from me, a retired cop, or ask any other cop, commission folks are politicians who buy whatever is cheapest, hence a shotgun, and usually don't know much about what they are buying in the first place. Don't go by commissions or Police Chiefs, ask a guide, native Alaskan who lives and dies in the villages by polar bears, etc..
They also recommend the .300 Winchester Magnum. Not exactly the cheapest.
Read the test articles I posted as well as the one where the many actually survived a bear attack using a 12 gauge and brenneke slugs.