This dowel rod and bit does the trick.
Got the Kentucky 45 down to 2.5" group at 25 yards, no swabing in between, which with my old eyes is good and considering it shoots a bit high at 25 I think it will tighten up at 50 because the sighting won't be so tricky.
The Hawken 50 at 25 yards closed down to 2" no swabing in between and should improve at 50 due to same, shoots a bit high at 25.
My new Zouave with .562 n .020 is awesome. Typical high at 25 and even 50 but still will put holes touching.
Shoots .575 minies just as good. No swabing in between. The added sniper sight is great for old eyes. Can't see the + but it's easy to center on target.