German 24cm case ID.

[HoldThePickle24]

Okay, this group has been awesome and helped me figure out 2 mystery items already. Now I’m trying to get 3 for 3.
I have this large 24cm case and I’m trying to figure out what gun it may have went to.
DETAILS:
Case length = 762mm
Case mouth ID = 248mm
Rim diameter = 274mm
Cast type = Tapered (slightly 251MM OD top to 262 OD right above the rim. Looks straight visually tho)
Stamp = PATRONENFABRIK KARLSRUHE, kriegsmarine M at 12 o’clock, VI, 1912, 319, ordnance symbol. Primer = C/12, 1/32.
Also the letter “I” and some unknown symbols near the edge of the rim.
It doesn’t *look* cut down necessarily. The top edge is perfectly flat/even and the edge grain is the same patina as the outside of the shell.

Any info or thoughts is appreciated!

 

[Hoeksel]

Unfortunately a 24 cm shell case with this length does not exist, it is definitely cut down. I expect the actual rim diameter is 275 mm, this would be a 24 cm L/40 C/95 shell case, normal dimensions 248x1032R275. Interesting is the 1932 dated primer. The symbols near the edge are frequently seen on German Kriegsmarine shell cases that are re-loaded.