While these SST sabot slugs will definitely fire in a smoothbore shotgun barrel, the manufacturer (Hornady) recommends their use only in rifled barrels for accuracy purposes. The difference is that with a smoothbore barrel, the slug will not rotate while in flight. It would be like throwing a football without a spiral. You can throw the ball, but it will not likely go as far or hit its mark. If you bought this product from us and would like to return it, please send an e-mail to customerservice@luckygunner.com and we'll take care of you.