That is an outstanding idea! Never considered using drill bits as pin gauges! Love this place.
Not home at the moment where my calipers are…brought it with me to play with in the evening. Gonna try shooting the .395 balls with .02 patches. They seem to press fit well.
The .410 balls are giving me 3-4” groups at 20 yards. I’d like a little better than that.
The grooves are very shallow IMO…these pistols likely date to the 70’s or 80’s. Could they have been built for slugs?
I will post a pic of the flintlock also when I get home. They both balance and point nicely.