I agree that this is very likely a southern rifle and that the lock looks like it began life as a flintlock.... not so certain that the rifle ever was. There is only one lock bolt on this rifle, but the lock plate has a hole in the forward part that would normally be where a forward lock bolt would be. This leads me to believe it was converted and repurposed for this gun. The trigger guard, imo, has a Virginia influence. What first came to mind was the "Bulls" who used one very similar to this style. Others did too, however. I don't count myself as an expert but just a person of interest. More detail, such as photos of the tang, entry thimble, toe, etc. would be most helpful in determining a possible identity. If you are familiar with the ALR forum you might post pics there. There are any number of fine folks on the forum that I consider very knowledgeable when it comes to these Southern guns.