Return of the Mountain Man by William W. Johnstone, Book #2 in the Last Mountain Man Series
Sometimes a man has to do what he has to do. If someone kills your wife and kid, you take care of the problem. And Smoke Jensen, the fastest draw in the West, knows how to take care of problems.
I'm not sure why I love these Westerns so much--easy read? the good guy wins? men are "men" except for the evil ones? I'm watching Longmire on A&E, too. Maybe next year I need to take my girl out to a dude ranch for a week so I can get all this wrangling and riding out of my system!