Vic,
I'm not sure his barrel has Henry rifling,it sounds very much like the rifling in my cousins 9.3x72R. It has very wide grooves and thin lands,which look like knives in the barrel.This gun is nitro proofed but he is afraid to shoot jacketed bullets, because of the thin lands.Without trying I wouldn't bet the farm on it, but it just seems such rifling should cut the patch.
Mike