Just assume you have gotten the "uselss without pictures" response- OK?
POSSIBLY a 3rd Model 1853 Enfield. This SHOULD be a rifled arm- rifling was relatively shallow, black powder and wear may have removed much of it. Type of rifle that brought about the mutiny of the sepoys in India. VR is her majesty, Queen Victoria (Victoria Regina).
Lot of reproductions out there, original is worth $$$. You need a hands on appraisal from someone that knows American Civil War period firearms.
Does your's look anything like this?
Pattern 1853 Enfield - Wikipedia, the free encyclopedia