According to Dennis Hiller (The Collectors Guide To Air Rifles) its a Haenel model X or 10. Maker: Either Haenel or under licence by Diana (Germany). Date: 1930s just prior to 2nd W.W. and may even have appeared just after the war. Value: £5-£20 [it is an old book]
Details: Nickel plated tinplate construction. Removable smoothbore barrel. 31 inches long with 8 7/8 inch barrel. Simple non-adjst sights. Top of the air chamber stamped 'X' and 'HAENEL' and a date stamp appears on the underside of the stock. [ So yours is Oct. 1937] Stamped 'MADE IN GERMANY' on the metal part near the stock.
Robert Beemans more recent book values them at $55 for a poor example upto $190 for an excellent one.
H.T.H.
Ian
Haenel Air Rifle
