Them Ballards are quite interesting rifles. Track must'a bought out someones collection,,I think they have three or four listed now. You could compare theirs with yours for a general ballpark idea,,,,and I'm sure ya would enjoy looking at them anyways.
Google up Track of the Wolf.com ...outta get ya there,,,then look under breech loading single shot rifles.
Got pics of your'n ? I'd love to see it.
MD