This is a rather tatty 7.65x17 SR Browning, Turkish Military property, but who is “M”? The primer idenitification might not be a clue, the case is pretty beaten up, possibly a reload. The bullet was a little loose in the case, I pulled it out with my fingers, the impression on the base of the bullet is also shown, possibly a clue. Gilding metal jacketted bullet, not magnetic. The case has a serrated bullet seating cannelure. The marking on the primer is as it appears on the picture, it is not just a “P” with a scratch.
There are a couple of minor variations of this round. They tend to match perfectly with a series of Chinese “counterfeit” .32ACPs I have. There is a chance they are Darra production, but I’m pretty sure they are Chinese.
I have this headstamp classified as being “Turkish” of unknown manufacture.
"Culots de Munitions Atlas, Tome II, page 64 gives the same national identification and goes on to say they were made c. 1914 for the Établissement J. Nikitis of Constantinople. However, it is only correct to point out that this book has an error concerning this headstamp. While not showing it, it says that these rounds have the Cyrillic letter representing the “B” sound on the primers. While the symbol on the primer does resemble that letter, it is precisely backwards to the correct Cyrillic “B,” so I believe that ID of the symbol can be eliminated.
There are variations of this round. I have one with a smooth case and one with a lightly-kurnled case cannelure. While both headstamps are the same, the letter font is very slightly different between the two rounds.
I tend to agree that these were made for Turkey, as there are many similar headstamps in 7.9 Mauser, for example (“Star & Crescent”) but that is simply my opinion. I have never found any kind of factory or national documentation (box label, catalog picture, etc.) for this headstamp.
The quality of construction, or lack thereof, leads me away from any European or Turkish source for these rounds. I will try to find and post some examples. I’ll stick with my Chinese or Darra, Pakistan theory, at least for now.