WW1 Artillery Dial 131st

My grandfather was a Lt. in France in WW1. Wilford Wolfie N. provided the soldiers' historical viewpoint. He served as an army artillery spotter, training at Camp Bowie in Fort Worth before being posted to France in August 1918.
He witnessed a German submarine attack on the journey across the Atlantic Ocean, saw the American troop buildup for an offensive and enjoyed a short leave in Paris, where he bought a pair of fancy boots that won him the nickname “Beaucoup Boots.” From my research, it is very likely they fired French 75 artillery or American copies of this.
I would like someone to identify what I think is a commemorative targeting dial recording the battles an artillery piece was engaged. Some said this was trench art and the battles are segments and one is missing. This is wrong. The back has a patent mark in french that spans the segments swords. "mod déposée' R.Patrouilleau.editeur" This is also not flat like a shell base and you can tell it was not sand cast in components. The edges are textured like an adjustment dial. In my opinion the open section allowed the view of some meter.
Update: I had found an angled brass part that had a central cylinder and 2 shorter lobes that was solid brass and had a brass bolt at the base. Unfortunately this was stolen, but I believe it was an abstract artillery cannon and was attached to the center of this base at an angle. I don't know if this was true trench art, as the base dial has the patent marks. It may have been a production commemorative piece or hand made art affixed to a production part.