Unusual (to me) French? 75x350 RENNES case

[jeff w]

Usually here in the USA when you run across a French made 75 casing (75x350 87rim) its the DE C marked type. I've never seen one like this and couldn't find any other photos posted on BOCN of this type.
Maybe all early French production looked like this? Has a slightly grooved (Bofors style) base - wonder if that had any purpose.

 

[flak18]

I have one like this but mine has black paint in the groove and I assumed it was for recognition of the type of load in ammo storage racking, as generally seen in a tank.
Just my take on the scenario

 

[M8owner]

The French did have various loads for their 75 DEC - a black cross or stripe across the bottom would be examples of identifying these. However, none were back circles.

 

[doppz92]

When it first entered service, the French 75mm gun had only shrapnell shells, in 1900 a HE version was introduced and in order to differentiate them in the dark the heads were grooved. This wasn't done for a long time and these cases are scarce.

 

[flak18]

Thank you for that info. I did not know that at all. We never stop learning, do we ? That's what is so great about this site.
My shell, with the groove on the head and black paint washed into it is made by Atelier de Rennes and is dated 1911.