Are the barrel bands brass? Really need pictures and/or more detailed description to be sure but it sounds like a Prussian M1809 flint musket converted to percussion. Many were imported during the ACW, used primarily by US troops, few if any were purchased by Southern agents. Though well made and usually in excellent condition when brought it, they were considered 4th Class arms and, when issued, they were used for training or in the Western Theater by troops in quiet areas. Their biggest problem was their large caliber (.71) that made them less accurate when using standard US .69 ammunition. Consequently, most went into storage and were surplussed quickly after the War.