What the HECK is this Luger magazine?!

[CavalryCombatant]

This morning I bought a big box of “ordnance”, brass & blanks essentially.  It didn’t cost a heckavu lot, and the guy I bought it from told me he got it all from a wwii veteran’s neighbor- who got it all from the veteran.  Now, almost all of the stuff in the box was wwii vintage, but there was some Head-stamps dating as late as 1975 on a belt of blanks.  So, I’m very hesitant to say the story adds much of anything to this magazine.  I did a couple hours of homework, and found nothing even similar to this one’s end cap.  
 

I tried a 9mm in it, and it does NOT fit, a 380 is also too small so I’m thinking it’s chambered in 7.65 Luger.  I tried doing research on the proof mark, but came up more or less empty handed there as well.  The buttplate with the grooves is the oddest part to me, and I was totally unable to find another like it.  It seems to be cast aluminum, I’m not ruling out homebrew but it seems a little too nice for that to be the case.  It locks up super well, and it’s all super solid if that’s worth mentioning.
 

My best guess, right now, is that it’s some sort of 1930s commercial or foreign export Luger mag, but probably German made?  
 

I’d really appreciate any insight if anyone can recognize it, or has any references that may help.

 

Many thanks!
CC

[daskrieg]

Type 14 japanese nambu

[CavalryCombatant]

5 minutes ago, daskrieg said:

Type 14 japanese nambu

I’ll be damned, that’s it!  I can’t thank you enough man, saved me a ton of time.. I was ready to bark up the German tree for AT LEAST another few hours.

[mikie]

Brilliant ID and congratulations on a nice pick up. 
mikie

[daskrieg]

Are you looking on selling it? Pm me if interested