If you want to narrow your search down, it's a pull-pin design, not a swing out cylinder.
The black screw on the front part of the frame? That locks the base pin in place.
Push the black screw thingie one way or the other (they are spring loaded and will only move in 1 direction), pull the base pin and roll the cylinder out. The base pin is probably small enough to use as an ejector rod for the empties. To load, reverse the procedure (hint: Rotating the cylinder after you have it in the frame seems to help get it and the base pin aligned).