Not to throw a monkey wrench into the works, but there was a Fred. Enderly who enlisted in Co. H, 2nd Ky. Inf., USA, in May 1861, promoted up to Sgt., mustered out in June 1864. This fits the carving on the gun. I have seen other US Enfields with soldier carving (Springfield Armory has at least one), and I have seen Enfields with Confederate markings that were ID'd to US soldiers (captured trying to run the blockade, or captured on the battlefield?).
Just another possibility ...