You may have phrased it better Tomo. the State of the art in WW II did not allow for the magazine to be fixed (stationary) in the vehicle and the gun to elevate and traverse changing angles and distances to the magazine. It took quite a number of years to get around this and the first post war vehicles to use auto-loaders used "fixed" magazines.
See AMX-13:
The turret bustle held two 6 round magazines. Another 24-25 rounds were in the hull of the tank but required the crew to dismount and load the magazines from outside the tank. Two magazines also meant that two types of ammo were available
without having to unload the magazine, although that does mean less of each available. Not a problem in an anti-tank aircraft, load it up with AP and go for it. More of a problem for an AFV. You need HE rounds but the round up the spout is AP and so are the next 8 in the magazine?? or vice versa? Please note that the whole upper turret elevated together, it was trunioned about mid turret.
Swedish S tank was next with an auto loader.
Gun was fixed in the hull and the driver acted as the gunner, pivoting the tank for traverse and using the hydro-pneumatic suspension system for elevation.
The problem in a vehicle like the Hetzer, which had a rather restricted traverse to begin with is not only is the gun breech/cradle waving about inside the vehicle, but now you want a huge magazine moving about inside also.
How far can you traverse or elevate/depress before the magazine housing hits the walls/roof of the hull let alone the crew that are left inside.
