It could well be that the gun was not completely disassembled during the case coloring, in an attempt to prevent warping. This would make sense especially if the gun had previously been redone.

I saw a 16ga SW today that had been recased. It showed some of the same traits. The seller at first told me he had done the work. As I began to question him, about his source of bone charcoal, etc, he admitted he had the work done by Ohio Case Color. It showed the same muted colors as this gun.

Pete