I'm not sure what you mean by falling out...is it pulling free of the reciever block? (part #39-51..dovetail block,front) If it is, then the way the tube is secured is by the formost barrel band,,,the -45 in our hosts schematic..take note thast there is a cross screw(39-164 magazine yoke tube screw) this tension the outer tube...the inside tube has a extebded pin thru the magazine plug(39-149) that engages the trackway in the magazine tube collar....if this trackway is worn or misshappen fromm years of use, then it will allow the inner magazine tube to rotate and drop out. You can add a "detent" of sorts by taking note of the pin position when the inner tube is rotated into place. You add the detent feature by using a sharp,pointed prick punch to peen a little dimple of metal into the pathway to restrict the tube rotation..It doesn't have to be a lot of metal....just enough to make a "SNAP" noise when the rotation is turned into place..OTHERS: The slot may be spread or the pin worn...check both...the pin may require replacement and you may have to reduce the width of the trackway with a bit of a pinch with a pair of pliers Make sure that the inside mag tube and its follower ar installed properly..if the follower has been inverted..then all tension is lost when empty
BTW The gun is made by Stevens and their factory model(s) are the 39A and 59 A...use that schematic and parts list...you can also replace the parts I cited;;;;;
Thanks Zeke, for the help, it is the inner magazine tube that is falling out, the spring loaded one that pushes the shells, I will try your suggestions and see what happens Thanks again.