The claim is that the Roper shotgun was the 1st repeating shotgun to use cartridges. The screw on (not screw in, as Jani correctly points out) choke was a bit later. The gun pictured in the auction does not appear to have the Roper choke device.
Look closely, muzzle is threaded and text says he does not have the device.
I knew it was not a screw 'in', thus my question leaving that word out of my question.
Where the threads are is somewhat irrelevant. A changeable constriction that screws to the muzzle nearly 90 years before the M59.
