When a friend of mine went to Russia to do some forestry work in Siberia, he stayed in a small town on the edge of a huge forested area. They were in country inhabited by the Siberian version of the Brown Bear, just as huge and just as tough. He was invited to hunt with some of the men and when he joined the group they were armed mostly with 20 gauge double barrels shotguns with a few Mosin Nagants thrown in for good measure. He wasn't sure about the 20, but with all the bear fur hats and coats in the area and surrounded by folks a lot older and slower than him he felt he could do OK. Those Siberians shoot everything with 20 gauge slugs and Mosin Nagants. Those 20 gauge slugs you 're thinking of using will deck anything that walks, crawls, swims, flys or tries to get away from you. The first gun I bought my wife was a Remington 870 in 20 gauge with a box of Buckhammer slugs. There were jokes about a shotgun wedding, but we won't go there.