Actually the tubes are the same length if measured at the rear spine.. the big difference, is one type was two pieces of stamped sheet steel, and the other one piece, and according to some, later a cold drawn formed tube, or an extrusion that required no trim or flash removal.. so if you look at start to finish, the later mags probably were not as material demanding .. but I think the trade off is, they ( the later mags) were actually more machining and labor intensive... A good plan gone wrong so to speak... Typical war time German ideaology...
..best to all, til...lat'r...GT