I'll through my .02 in for the 20 in o/u. For pheasant and grouse it's plenty of gun, easy to carry and fun to shoot.I personally would go the 12 only if you wanted to use it for waterfowl to. I like my pump 12 for that as I have used that 3rd shell to many times and some of those ducks and geese seem to be able to eat up shot.