PECATONICA's H & A Underhammer

[4570tc]

Has anyone built a H & A under hammer from PECATONICA? What does the not threaded end of the Breach plug look like? It did not come with a breach plug. My attempts are weak, not holding the barrel/ Receiver solidly. I have tried milling flats, Dimples where the set screws go? anyone have a picture of this part?

Thanks

 

[JHB]

The breach plug is round with a wring fit in the receiver. There are flats milled for the set screws to lock against.