Rob,
I'm not going to speculate on a possible maker. However, I to see a lot of Union/Snyder County in this gun. Mostly in the overall outline of the buttstock, the general design of the patchbox. However, there are also things about this gun that are not typically seen on guns from that neck-of-the-woods. The push-button patchbox lid release is not what you expect to see on a Union County gun. A release stud that protrudes through the rear-center of the buttplate is much more common. Your gun looks to have been converted from flint to percussion. The lock sideplate is not of the type usually seen on earlier Baum or Dreisbach. The sideplate on early Union County guns often have deep cut horns or lobes on either side of the head of the main lock bolt. Lastly, the rear entry pipe does not appear to be made from two separate pieces of brass. Union County guns commonly have a rear pipe made by riveting and soldering a tail piece to the pipe. The rear pipe of your gun does not appear to have an iron rivet in it. There were many gunsmiths that apprenticed in the Baum and Dreisbach shops and then moved on to Western counties of PA, and further West into OH, IN, etc. Maybe your gun was made by of these gunsmiths that learned the trade in or near New Berlin then moved on to a place where there wasn't so much competition?
Mark Loudenslager