When you look at the barrel/tang junction the join looks like doesn't quite match up The barrel is high on the left side and low on the right , The lock has never been cleaned up and polished inside or out , , it is still showing casting marks on the frizzen , which makes me wonder if the frizzen has been hardened properly . I'd say this definitely is a kit gun which has been put together by someone who did little or no work in it , The lack of work on the lock could be the cause of a poor spark . I doubt if the hammer has been replaced , it matches the rest of the lock in it's lack of finish and detailing