Is this the missing link??

[doppz92]

I found these two casings this weekend, but it's something I never seen before. The head part is made of brass, but the body is made of copper, hence the colour difference. The caliber seems to be around 107-108mm, length 140mm and head 118mm. The casing is extremely well made, and I don't think it's been cut, both are identical.The primer, isn't the one of these casings, the thread is different, it looks like a German primer but there's no marks what so ever. On the head one can read: R152 on one and R140 on the other, and both have CC in an oval.
The shape of the head reminds me of some sort of French navy shell, but that's all I can think of.

 

[HAZORD]

Schneider had a number of calibers using the concave case head design. I haven't seen this size before.

 

[Hoeksel]

Interesting item....primer looks Russian to me, and Russia used a lot of Schneider-Canet guns which is the only type I know that has concave bottoms. These guns are mostly navy/coastal guns so normally I would guess these cases are cut down (even though they are same length). Based on the rim diameter (that is what you mean with 118 mm right?) and assuming French or Russian only 1 case comes close.....a 105x455R121 Schneider export case but I have no details if this case has a concave bottom.