Found this awhile back on some 1903 discussion. It appears to be a SA GHS rebuild stamp on this 1903 stock. Note the bolt is serial numbered with electric pencil which could indicate the following: it was a National Match rifle rebuilt for WW2 or a USMC rebuild as they often numbered their bolts to the receiver during pre WW2. I would rule out USMC as they would not have used the SA GHS stamp even if they marked their rebuilds during this period.

Years ago I had a friend in the Boston area that had a rebuilt SA SPG stock with two equal sized holes converted to trap door butt plate. He always claimed there was also a faint SA GHS stamp, which might indicate it was a rebuild stamp. The very early rebuilds on no trap stocks were without a rebuild stamp, only the additional non serif P in a circle

Anyone else have any additional information ?