If you have a shotgun already and have a mod choke screw in all you need to do is buy the new FEDERAL TRU-BALL slugs..they have to been seen to be believed...they are designed for the smooth bore and shoot groups as good as my rifled barrel..they are the best going..I've tried at least 7 other types and none even came close out of the smooth bore..I shot a big ole OHIO whitetail last year with one and smashed it in it's tracks..TRY EM ...save yourself the money for very little if any gain.....