Originally Posted by
bronko22000
They do make pin gages that you can use but the grip end of a drill bit works for this purpose. Just FYI if your flash hole is actually say .030" you won't get a .030" bit in there. Likely the smallest you'll get in is a .029" or maybe if both are perfectly round a .0295".
Yes but a #69 (.292) and #68 (.031) is probably within specs of the Breech Plug Flash Hole. Personally I don't know of any gun that that is not true for, But I don't own them all. Thanks for the info, I do use pin Gauge ZZ Minus for checking bore diameter but I think the pin gauges would cost a lot more for a set to cover most Breech Plugs.