Chamber size is Typically engraved on to the barrel too. For anyone who is unsure with the choke dimension or chamber length within your shotgun, please reach out for the producer of the shotgun for guidance. DjinTonicDjinTonic 26k11 gold badge3939 silver badges113113 bronze badges 5 Now that is one detailed, https://30-30-1000-rounds01936.blogminds.com/5-45-x39-ammo-for-sale-things-to-know-before-you-buy-34799862