i have this casse since years in my collection but never found info what a gun used this casses .
headstamps on bottom of cassing
PATRONENFABRIK KARLSRUHE OKT 1917
5 SP 255
FRIED. KRUPP A.G 12
CASSING WEIGHT 5,5 KG
DIAMETER ON TOP 19 cm
from botom to top diferent diameter the casse is conic and have a bord look pics .
thank for all help for id .