Paul Crosnoe currently has a Sumners hammerless 20ga with modern nitro reproof in his inventory. I used to own that gun. Shortened at some point, likely for a youngster or a woman, then a piece added to the buttstock (pretty decent job). I've had thoughts of reacquiring it at that price.

Sumners went out of business long enough ago--well before WWI--that there's not likely to be that much information on him. But that 20ga I owned showed that they turned out some pretty nice stuff.