CC, I know I have a fairly intact fired roundball from each barrel but I couldn't locate them. The unfired balls were .830" and these each had a small "belt" measuring .8270" and .8265" as near as I could measure. I don't recall any distinct facet or groove markings on them.

Looking over the barrels just now with a bit of lube in the bores to help the grooves (such as they are!)stand out, it looks like they make a 1/3 turn in the not quite 29" inches from the chamber mouth to the muzzle, so I'd call it in the 1:90" +- range. They could easily be 1:100 as they are very faint. I couldn't count the grooves (you can barely feel them) but I'd guess 10-12 of a very shallow polygonal-type rifling.

This gun has fold down sights for 50 and 100 yards. I recall reading that it was meant for 1250gn conicals rather than round balls but don't remember the source. It is slightly undersized for an 8 and was proved at 9/1 despite having the "standard" 3.25" papercase 8-bore sized chamber.

As an aside, I've always found it intersting that, based on Greenhill's formula, the twist required to stabilize a conical drops dramatically as bore size increases. This makes 1:90" twist adequate for a 1.15" long bullet in this case and the 1:100" twist (normal associated with roundball guns) good for 1.5" conicals in 4-bore.

Bob