Trooper Dan, I have one book, Savage & Stevens Arms, 1864-2003. It only mentions the M340 by reproducing a full page Savage advertisement from March of 1957. I have another book, Savage & Stevens Arms & History, by Bill West. It only shows an undated full page reproduced ad. It mentions a 340 "Bolt Carbine", but does not show a picture. The ad I did find in this book, shows a 340 Standard Model and a 340-s (little "S" used) listed as a "De Luxe" model. Have you searched eBay and Amazon? You may have the same problem I had when I could find no information on the M219/220 single shots. I paid $125 for one of those books and all it had was a one page reproduced ad from the early 1940's about these two guns. In frustration....I wrote my own book. Give it some thought and good luck to you. Let us know how your search goes.