I have a 657-2 41 that I got as part of a larger collection I bought. I didn’t get boxes or spare parts for it. It came with a cheap taco red dot scope mounted on it and when I toook it off I realized the rear sight is missing. I ordered one from Numrich but it is too short. The hole in the tang didn’t line up with the hole in the rail. So in addition to finding a rear sight I would like to know any additional info you guys can get from the serial number. Thanks!