I just recently received a Webley Junior .177 air pistol from my grand father. I would like to know the date of it and possibly a price range. There's two numbers on it. One on the left side of the gun between the trigger and the grip it says J21770 and on the front of the gun it says 770. I have googled a lot and have found similar guns but with different types of grips. Does anyone know anything about this gun?