How do you find information on WH Davenport shotguns?

There's not a lot of information available and most authors disagree on that. Carey's American Firearms Makers says the company was in Norwich Ct from 1855 to 1894 and made single shot percussion and metallic cartridge rifles. Vorisek's Shotgun Markings lists 4 different names, W.H. Davenport Firearms Company, W.H. Davenport Arms Company, Davenport Arms Company, and W.H. Davenport & Co., and gives dates from 1878 to 1910. The Standard Catalog says they made single barrel shotguns from 1880 to 1915 and single shot rifles from 1891 to 1910. Traister's Antique Guns says they made single shot and double barrel shotguns in Providence, RI. The Official Price Guide to Antique and Modern Firearms says single and double shotguns in Providence, 1880-1883, and Norwich, 1890-1900.