For all things H&R check out Graybeard Outdoors. First off some barrels will lock up tight, some require fitting. These are not Encores, a direct fit is a gamble. Other shotgun barrel can be used except 12 ga Ultra Slug and 10 ga. The only rifle barrels safe for your frame are 22 Hornet, 30/30, 45/70 (Trapdoor level loads) 357 mag, and 44 mag. Use any other rifle barrels and you are holding a hand grenade. Rimfire barrels can't be used other than the very hard to find Versa-Pack barrel.