The easiest argument someone could make on where the photo was taken in France, would have been at St. Nazaire France. If it was taken there it would have been taken earlier in 1917 than my Dec 1917 date.
The tents and even the uniforms of the Marines at St Nazaire, would match the photos really well. Here are a few pics form St Nazaire France. Photo's are courtesy of Steven Girard.
Even though St Nazaire would be the most logical choice for someone arguing this. I sort of have a hunch it wasn't taken there. The reason being, the photos in that block in the AEF book are later and none show a location as being taken in St Nazaire. They were taken in training further inland in France.
The other thing that gets me. WRA states the Marine A5 rifles ended up going to a unit close to an Army repair Depot in France. WRA doesn't name the Army camp. But the Marine documents do. The Marine documents name the Army Camp, and say that the Army repaired all their A5 rifles that broke and kept them serviceable for the Marines. Also the Army had a long distance range set up at this Camp that the Marines could sight in their A5 rifles and get target practice with them. These early Marines were not school trained snipers like later in the war. So from everything it says, it sounds like these Marines were literally shooting the Teslescopic sighted rifles for the first time at this Army camp.
The most interesting fact, this picture is a ARMY signal Corps photo, and this Army Camp where the Marine A5 rifles were serviced and sighted in, was one of the major headquarters for the Army signal Corps. So I have a hunch the Army Signal Corps took this pic of a Marine who was probably there sighting in one of the new WRA rifles.
Other than just the generic France location, I doubt any official documentation will be found that says the exact location of where it was taken. I just have a hunch it was taken by the Army Signal Corps at this Army Camp in France. But I can't prove it. It's just what makes the most sense to me.
He was posing for this photo and not sighting in on anything, as the A5 sight in that location, wouldn't have a good sight picture. Also if the A5 scope wasn't modified in a way, the bolt would hit the A5 scope and you had to push the scope forward to cycle the bolt. The Marines fixed this later on by modifying the A5 scopes in a way that the bolt would clear. So that might be as well why the scope was pushed forward as well, to cycle the bolt.
But as far as location, a very safe argument would be St Nazaire. I just have a hunch it might be at that Army Camp. I just can't prove it.