history i can help a bit .. the mag .. i'm in Australia so sorry there
the Deutshe Werke model was a 2nd generation after the original designer and maker went onto other things
he worked out how to do make it cheap and very reliable and sold or did a deal with the Deutshe Werke folks , the pre Deutshe Werke version is very much a collectors item and brings a high dollar
they have a excellent rep as a target pistol with one gent here still pulling great scores for a almost 80 year old firearm
The Deutshe Werke was ( i believe i may be wrong ) used by one of the US shooting team to get a perfect score against many other supposedly better weapons and shooters to win a world shooting title in the 30's
your magazine may be interchangeable with the 9mm version but check with a expert as i'm not sure when and what serial number they changed the butt lock
i worked on the gents one here and it needs no work .. its a great pistol with over 50,000 rounds through it that we know of ( not bad eh!!!)
we strip it bath its and reassemble it and its still a very nice pistol
do you mind if i ask what you paid for it ?
i've not seen one sell that i remember the price and as a semi fan of the thing ( it impressed me a lot) i would not mind looking for one myself or offering the gent here what it is worth
all up a nice weapon ..
PS web site for you from my bookmarks