Upvote:5
Quite a bit of information can be gleaned from the description here (though a photo and measurements would still help greatly).
Most of this can be compared to the answers about a similar shell in What can I learn from these WW1 shell cases?
A discussion on the greatwarforum has info concerning the 75 DE C designation.
ARS is also mentioned in the headstamp codes listed here
A discussion on marking on similar 75mm shell casings can also be found at forum.cartridgecollectors.org