CombatAK
Hooligan #12
Hornady makes .36 cal balls that are .350. If those lead balls are handmade, could it be a .36 cal? It is a beautiful rifle nevertheless.
Put something between the nipple and the hammer to soften the blow and lessen damage to the nipple.
Leather works well.
Or the maker got a lock from somewhere which may have been intended for a fowler, or previously used on a shotgun.