[Buffalochip]

I took the liberty of loading one of your earlier pics into Photoshop and messing with the contrast and brightness a bit. If that receiver and loading lever aren't casehardened, than I don't know what is. The hammer even seems to have some coloring. As you pointed out, the remainder of the gun metal is uniform in color and doesn't exhibit mottling due to age. I think some pics, taken outside without a flash and out of direct sunlight is all that is needed to conclude if it is casehardened or not. Now if that casehardening is original...