If the bottom is nailed on it is unlikely to be a cartridge box of any kind. Nails would work loose under the weight of the ammo. The ones I have seen are almost always made with dovetails, or finger joints for the more inexpensive cases.
W Richards Liverpool was a fine maker. Not to be confused with the multitude of continental junkers utilizing the Richards name to capitalize on Westley Richards’ reputation. William Richards was the real deal.
Lloyd3 has a W. Richards boxlock ejector that is well above par. Nice long length of pull and the stock bent for a lefty, which, I once was. Having to shoot off the right shoulder has cured the lust I felt handling that old gun, but, you are correct, a fine gun maker, indeed.
Best,
Ted
