As I mentioned before, I have never owned a gun and never will, but I have heard great things about the Mossberg 500. You can buy the combo (with 18-1/2" and 28" cylinder bore barrels) and, for about a hundred fifty bucks more, buy a 21" rifled barrel for firing Brennecke slugs. Since the barrels lock onto the breech "extender", you could mount an Aimpoint on the extender and have it work for all three barrels and loads, although it might be overkill for the 18" barrel firing #7 dove LOL!!.

The Brennecke slug, by the way, drops about 10 inches or more over a hundred meters, but is still accurate out to that distance. It will work fine on mule deer at those ranges; and, with all the other options, from #8 target to 00 to incendiary rounds, there isn't much you can't do with a slide action shotgun.