As you say Helles, probably something a chap got his hands on and sold local to your area. When i had my firearms permit and was a member of a Rifle club i had the pleasure of firing a musket, caplock i think it was, ex American civil war job.
The size and weight of it is not something you would forget.
No wonder not many could afford them, even deactivated a prize worth having.
God help us,
Don't send Jesus,
This is no place for children.