Hello and hope everybody is staying well. I am planning to make my own percussion powder drum from scratch for a future build. I currently have good information on all the outside dimensions of the screw in drum. However I am clueless about the internal diameter of the fire hole. I think it is an 1/8" diameter, but that is only a guess. Could someone please offer there opinion on the optimal fire channel diameter. I am planning on producing a drum with 5/16" male thread. Thanks in advance for your input.