Guys,
1. A question for Paul Griffith: it would be interesting to see a photo of your rifling cutter, perhaps we could all learn something new. I was thinking that a head that is 0.005 smaller than the bore would give very little room for the cutting chips to go, chip clearance. With the cutter that is posted on the thread "making a cutter for rifling" the chips are rather large, much larger than filing chips/dust. There is plenty of clearance for the chips here. I oil the cutter, mostly to make these large chips stick to the rifling rod so that they can be removed after the stroke and do not remain to be dragged in/out and maybe scratch the bore.
2. A comment for ironwolf: I care. I like to make reproductions of the 18th c guns using original tools, methods and materials to a great extent (yes, I do have corrective lenses on my eyes and a smallpox vaccination, too). This leads to a 7 groove barrel, irregardless if this is the best, most accurate or whatever. Remember, that if we actually make an 18th c gun, that certainly 80% to 90% of the work is in the gunlock and barrel, alone.
Jim