Well, since you asked, David, I'd go with about a 24" twist, grooves .006" deep and twice to 2 1/2 times the width of the lands - whatever that works out to for land width - very narrow in any event. You'd have a bullet rifle that would load easily with grooved lubricated or paper patched bullets and shoot exceptionally well up to about 350gr. bullets. This, of course, depends on weight of barrel, of course. I'd go underhammer as in an H. Warner or W. Billinghurst style.