Help with Headstamp for shell please

[warhammer]

High Definition pics here shell casing - Imgur

Found in the WW1 chest with 30 other items, My relative served in France, 141st artillery or in a loaned MK IV british tank or in the 41st infantry.. ( WA. OR, ND, MT, ID, combined national guard.. there are clues, but no definitive answers yet..