The gun is labeled only London and Lovell Arms Co. Boston. It has Birmingham proofs, top lever, small hammers, Purdy double underbite. The replica buttplate site has the same buttplate attributed to J.P. Clabrough. I'm guessing it dates to 1890's.

Drew's photo had me a bit confused, as I thought perhaps it was a browned barrel which had turned black under the forend.

I think I'll see about making a boiling tank and try to make it black and white.

Thank you all for the education.