Apparently D. Kirkwood was a well-known gunsmith....I found this on the shotgunworld.com forum.

"Information from "Sides by Sides of The World" written by Charles E. Carder. In 1874, Scottish emigrant David Kirkwood founded a company with a partner Henry Mortimer. They made high quality breech loading guns. This company was located at 23 Elm Street Boston,MA. This company continued in business until the 1950s. Since I can't tell from the photographs if your gun has damascus barrels or not, you should take it to a qualified appraiser like a a gun dealership, a knowledgeable gunsmith or a professional appraiser (not a flea market type) for a hands on evaluation."