I had a D M Lefever "cross bolt" on display as Vegas with a more subdued "S" grip - from the Syracuse era of that company. None of us had ever seen another Lefever with that grip, but it is found on some other shotguns from that area. There is some very simply border carving on the gun, not a leaf pattern like these rifles. The Lefever would have been made circa 1902 or '03. Maybe your "Unknown" was working near Syracuse and later moved to Chicago.