Here's a pic of some of the variations. On the left the 2 different styles of vertical adjustment screws are shown while on the right are contrasted 2 of the different-styled knobs.
Please note that the vertical adjustment screws were originally left-hand with rather coarse thread and also had their bottom ends made captive to the back of the slide while the later screws are finer-threaded in the right-hand direction and are not captive. I don't know the exact transition date but 'assume' it's ~1945 or so. The horizontal screws underwent a similar transition.
The knobs are both prewar and it's easy to see which is the taller 'target' configuration. Sorry I don't have a target horizontal knob to show, but it's slightly thicker than the standard one with more-pronounced knurls.
HTH, regards, Joe
