After restoring the Diana 48 from 1925/30 ,I noticed a few differences between them.
The early one is the one on the bottom of all pics.





Early one has "DIANA-LUFT-GEWEHR" on top of the barrel just in front of the rear sight, the later one doesn't.



Cocking arm levers are different.



Loading tap cover plates differ.





Pressed chequering versus hand cut chequering.



What both have in common, is a nice piece of wallnut!





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Frank