Jc5, I trust your call, but what clue do you see that indicates pre 1915? I'm still leaning towards post war.

ALL of the factory sporters are pre 1915 or post 1918, no?

I am an info sponge when it comes to figuring out the dating of these commercial arms.
Solid info is hard to find, just scattered tid bits. I am trying so hard to pull my notes together and make sense of it.

Perhaps there is a date code marking with the proof marks? That would nail it.