WW1 French Navy cartridge case?

[Vasco Da Gama]

This cartridge case turned up recently and I cannot immediately identify it. The headstamp appears to be French in nature, potentially first used in 1916 and again in 1917. The primer is what points me towards the French Navy, I initially thought it could be a cut down 65mm Model 1902 case, but the rim diameter is wrong. I also thought about a propelling charge for a surface ship torpedo! Pictured against a 65mm mountain gun case for comparison, Very glad to be educated! Length 208mm, mouth 79mm and rim diameter 87mm, the primer diameter is 17mm.

 

[Gspragge]

Here is an explanation from another with thanks ~
These special cartridges cut to a length of 205 mm were intended for
firing 150 mm (6 inches) bombs from a trench mortar FABRY
which appeared late in the war (1917) and was light enough
to be brought up in first lines during an attack ; it stayed in service up to 1940.
These cartridges which are rather rare they have
the french navy primer screwed in and also the stamping from
Toulon arsenal along with the dates. The french navy arsenal were
not much busy so that they were required to make ammos for the Army.

 

[Vasco Da Gama]

Thanks Gordon, really interesting, every day is a school day!

 

[Gspragge]

Here is more ; From the 1917 manual on French Trench Mortars ~

 

[kz11gr]

Hi

I do not agree. For me, not for the 15cm mortar.
This case come from a naval munition, (typical primer & headstamps)
May be used to launch Torpedoes , or for submarine bombs thrown by a machine like Thornycraft. Or for blank fire (Salut).
15cm Fabry cases are 112 mm long. (65mm mountain shortened) : 65mm x 112mm
15cm Model 1916 (75mm DEC shortened) : 75mm x 200mm

 

[Alpini]

Yes it's clearly a naval case with naval headstamp and naval primer. Sadly it's one of the worst documented parts of 1st WW ammunition.

 

[Hoeksel]

In my former collection I had at least 5 different French unidentified navy cases that resemble yours.
1) Made from another case.
2) Navy primer.
3) Many reload markings.
4) Unidentified (based on dimensions).
5) Often rather rough mouth, indicating they may indeed be for purposes different then shooting projectiles.