Drum Magazine lower door hinge placement

What is the logic of having the lower half of the drum magazine door hinge attached to the magazine mount?

I have recessed the hinge into the drum mag(so it fits into the mount) and the door and drum magazine stay together. And I can swap out the stick mag mount anytime.

readyman, you are correct in this problem, the drawing looks good but doesn\'t work.  Your solution looks good although most builders just make a dummy drum for display anyway.
Dick C.