Howdy waterfowler, I am in just the opposite situation as you. I have been slug gun hunting for quite some time (whitetails mainly), and am now tryingbowhunting. Here is my opinion on slug guns. I have tried smooth bore shotguns and full bore slugs, a bolt action Mossbergrifle barreled gun, and now have an H & R Ultra slug hunter. The ultra slughunter is by far the best rifle I have used for these types of hunts. The last whitetail I took (on a "short range" hunt) was at an honest 150 yards, as per Leica 1200 rangefinder, and a good rest. I shoot the Winchester 12 gauge Platinums and they group great. I have not found a single pump or auto shotgun that combined with any replacement rifle barrel, shoots as well as my H & R Ultra slughunter. The good news is that you can get one of these complete rifles for just a little more than you are going to spend on that barrel upgrade, and you have a whole other rifle. I would recommend one thing though, consider the 20 guage over the 12 guage. The 12 guage is pretty stout to shoot, and unless you are hunting dinosaurs, the 20 gauge version will be plenty of rifle. Good Luck!