Screw in choke tubes can be added to some fixed choke shotgun barrels. Finished wall thickness is the primary factor to consider when adding a screw in choke tube to a fixed choke barrel.

For example, we use only Dave Manson Precision Reamers tooling here, so the largest diameter that the choke reamer or tap will cut when installing a Remington Choke tube is .822″. For safety reasons, the absolute minimum finished wall thickness we allow is .015″. As such, if the bore and outside diameter of the barrel are concentric the minimum outside diameter the barrel can be is .852″. However, keep in mind that the outside diameter of most shotgun barrels are not concentric to their bores. As such, the minimum finished wall thickness on the thin side of the barrel will still have to measure .015″ or greater once the choke is installed regardless of how thick that makes the thick side.