Found it here. http://codes.ohio.gov/orc/2923.11
(L) "Dangerous ordnance" does not include any of the following:
(1) Any firearm, including a military weapon and the ammunition for that weapon, and regardless of its actual age, that employs a percussion cap or other obsolete ignition system, or that is designed and safe for use only with black powder;
So I guess I can buy one.