Winchester Model 40 with RA-P stamp

[FP1201]

We had a Winchester Model 40 come through the Shop for service, and I notice a Military inspectors stamp in the stock "RA-P" which usually stands for Raritan Arsenal Proof, no other military markings, and so far haven't found where this was used by American Forces, still I'm certain of the stamp having seen it on 1903's.
Anyone with insite?

[lyman]

may have been used on a post (for the skeet or trap range) or used as a trainer for AA ?

speculation on my part,

[FP1201]

may have been used on a post (for the skeet or trap range) or used as a trainer for AA ?

speculation on my part,

My thoughts too
The owner said it was his Fathers who was in the Army-Air Corp when he was very young.

[Johnny P]

I have always heard that the P was the initial of the inspector/foreman of Raritan at that particular time. I have seen rebuilds with both the RA-P marking and a P proof marking on the wrist.

Some facilities marked any weapon that came through whether rebuilt or not.

[FP1201]

The Shotgun does not carry the "P" proof mark we're used to seeing.
Given the very short run and number of these shotguns produced, I'm thinking the Army may have bought a few for either the Skeet Field at Suffolk or use at Raritan.

[FP1201]

Link to some History of the 40: https://guns.fandom.com/wiki/Winchester_Model_40
I suppose the owner could contact Winchester on the off chance the Historical Society might have a file, but that's on him.