That is a nice looking rifle and looks to be "unmessed" with, which is rare.
I think it is a lot earlier than Civil War period, but I'm not one of the more knowledgeable longrifle people on this forum. The hammer may not be original, but it is pretty cool and the counterplate is nice as well.
The triggerguard is very distinctive. There are a few rifles in Whisker's Behold the Longrifle, that have the same style triggerguard. Whisker labels those rifles as being from Ohio.