The Mountain gun is stanless and has a lighter weight, thinner barrel. The frame is the same.

I actually perfer the handling and pointability of the heavier profile. A personal choice.

I've worn out 2 M29's since 1973. The first one was fed nothing but 22gr. 2400 and 250gr. Lyman Keith's and only lasted 3 years of quite heavy shooting - yearly average perhaps 2,000rounds after the initial spurt of 2,000rounds per month for 3 months learning to shoot it with accuracy to 300yards.

Heavy loads are/were used sparingly in the next two guns.

If a shotgun with GOOD slugs or round balls isn't available (first choice), then a handgun could work on bears, in the right hands.