I doubt this is an Auer rifle from Louisville...I have 3 and have handled several others. Could you post 2 additional pictures: 1) reverse side showing butt and rear side facing with lock bolt washer; 2) cast nose cap from slightly underneath so we can see bottom detail and one side. All the Auer rifles I have seen show his Swiss heritage in their lock bolt, which is mounted significantly lower than on this rifle. I'd think the maker was W.B.J.K. per the lock and barrel mark. Only maker I can think of whose name comes close...and dates were ok...was W. B. Keable of Jackson Co., Alabama who was there at least for the mid-1850s to mid-1860s. Shelby Gallien