Hey Doc,
It was most likely at the factory as an unused spare or frankly, could have been in the parts area - most likely this was left over when they moved away from the rolled nickel mag type in the 1936 timeframe. Since "1936" had both types of mags, and your's was not "Accepted" until after the war with that die - it simply means it wasn't issued with a wartime production HK. However, it doesn't detract from it's originality, and quite frankly - is a terrific example of the post-war proof. Good for you - and Congrats!!! <img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />