T C N headstamp - 11mm Mauser

The headstamp is T C N or some combination of those 3 letters. Is this Turkish?
The case has all the dimensions of a normal 11.15x60mmR Mauser with the exception of the small primer. The long lead bullet has a coating of what looks to be dried grease or lubricant of some kind which actually has a brownish tinge but it looks grey in the scan. The cartridge is heavier (691.4 grains) than a normal German 11mm Mauser and has a .441 bullet.
Anyone know where it came from and/or who made it?

Phil, that hs of yours is a bit of a surprise. I think that it is supposed to be “T S N” and the C is actually a “damaged” S. Notice that the bottom of the “c” doesn’t reach the raised base part whereas the other letters do.

Here is what I have on that TSN hs:

"There is also a hs generally regarded as “TSN” hs on a 10.5x61R (MB131) and also on 11.15x60R (MB145) Mauser cases, which has been speculated to have been produced c1875 for Schumacher and Niebecker, Gunmakers of Soligen presumebly meaning Niebecker & Schumacher GmbH & Co - metal forming company of Iserlohn, Germany ??).

This is unconfirmed as “T S N” may be “N T” of “S” or poss “SN T”. TSN may however, just stand for some unknown ammunition company."

Let’s hope someone else knows more ?

Thanks WBD

I can see where it very well may be a broken S instead of a C.