Have this 12 guage Glenfield Model 50, 1970's production. The chamber length is not marked. My research seems to indicate, it is built with the same reciever/magazine/chamber as the 3inch Goose Gun, and is in fact a 3 inch shotgun. Does anyone know for sure? Will cycle and chamber 3 inch from mag, and will eject empty 3 inch shells. Short of actually firing 3 inch, can have my gunsmith check it, but hoping somebody may know.