60x64R German L/21 Boat Gun case

[Falcon]

I got a 60x64R case at a boot sale today, can anyone post a photo of a round with its projectile in place, or a diagram of a loaded round? The case mouth actually measures about 63mm, but the case is correct length and does not appear to have been cut down. The extra few mm makes me think that this could be a round that had its driving band inside the case mouth. Is that true?

I am sure of the German Navy connection with this case as it had the crown over capital M. The full headstamp is: "M PATRONENFABRIK #KARLSRUHE# V 1917 143. ("#" Indicates flaming bomb markings). Any photos/drawings/information would be helpful. How common is this case? I have never seen one before.

 

[waffenamt]

Falcon,
can you post a piccy mate?
best

waff

 

[Quatermass]

6 cm/21 C/98
6 cm/21 S-Bts KL/21
6 cm/21 Bts KL/21

Originally developed as a small anti-torpedo boat gun. During World War I mounted on some landing craft and also used as a landing gun. Used during World War II on some small coastal defense boats and submarine chasers.

Information from:
www.navweaps.com/Weapons/WNGER_6cm-21_skc00.htm

brass case 60 X 64 R, rim diameter 83mm, separate loaded.

 

[Falcon]

Here's the pictures:

Case (with AA battery for scale)

Thanks for the information quatermass.