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It could be an orphan magazine to an RSHA/SS Walther. If it's for a PPK the gun was made in 1940. If you could find the owner of the gun it would be worth whatever he'd pay.
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A few questions: Is it a bottom release type or is there a cutout for the mag catch on the front near the top? Is it marked with just the Walther banner or the banner and caliber? If it has the caliber is it marked "m/m" or "mm"? What type of finish is on the mag body...polished blue, dull blue, or grey? Are the numbers original factory or restamped? Also, double check that it's a PPK mag and not a PP.
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Without knowing more about the magazine it's not possible to say what type it is or what it's worth. A ballpark guess without knowing more would be $75-$150. Photos or a better description would be a big help.

 

Do these help?

 

ppk Mag.

Cant find the gun owner because someone at work gave me this Mag that he found in a abandoned car.It has a cut out up top,the serial # is factory.It appears to be a dull gray with machine marks plentiful.It definitely says Walther ppk 7.65 m/m thanks for the help!

 

Cant find the gun owner because someone at work gave me this Mag that he found in a abandoned car.It has a cut out up top,the serial # is factory.It appears to be a dull gray with machine marks plentiful.It definitely says Walther ppk 7.65 m/m thanks for the help!

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Oh yeah...the photos help...
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It's a correctly marked 1940 PPK magazine. The PPK was originally issued with two flat bottomed numbered magazines. The serial number is in between two known WaA359 marked examples: 303534K and 303861K. If I were a betting man I'd say that the PPK your mag was issued with is from the same military contract. Based on the condition and serial number I'd value it at $100 - $150.
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To find the owner you'd register the serial number in an orphan magazine database. Or sell it to a collector who will spend the rest of his life looking for the gun...

 

Thanks Milspec! Had no idea it was that old. Dont know much about Walthers, Im mainly a 1911 guy! Thinking about putting it up on gunbroker to help finance my AK.

 

Maybe it is still in the car! It was found in a car at the dealership.one of the make ready guys gave it to me.they give me all the gun related stuff,No actual guns just yet! only accesories. lol