M1917 stock markings

I just acquired an Eddystone U.S. Model of 1917 most of the parts are Eddystone with a few Remington and Winchester parts. I noticed what looked like a Remington R in the channel for the bolt. The front of the stock is marked E. The SSAA stamp appears on the left side of the stock. The only other marking is inside the barrel channel. It appears to be a 4. What do you think about the R stamp I have not seen one in that location before.

The "4" in the barrel channel is probably a common subinspection mark. Springfield and Remington M1903 stocks were commonly stamped in that location.

The "R" in the bolt handle inletting was probably stamped by the San Antonio Arsenal when they gauged the stock during overhaul. That's my guess. I have not seen that before. The stock was clearly manufactured originally by Eddystone.

J.B.