As with LR1000, the savage is the only one I'm aware is made with rifle on top and shotgun on bottom that's suited for taking deer. 30-30 over 12g. You can find plenty of over under shotgun onlys, that can takeboth slugs and birdshot. However, it mustbe either 12g or 20g if this is to be done, asthey're the only with highly availablerifled slugs and birdshot loads.JW, why smaller than 12g? It has great versatility. If it must be a rifle and shotgun barrel, and your plan is to take a bird while deer hunting, cocking the hammer and switching the pin to either barrel will be slow and perhaps cause confusion when a deer shows up. To keep ethics in it for the animal, both barrels should be loaded for deer until you've made your mind up to load up for birds only, or vice versa.