This is a Tyoe 3 - Oval Cut - Low wood- Short channel Stock. Appears unsanded. No "P" proof stamp. Minimal dings. No M-2 cut.
Sling channel appears to have stamping of a "U" followed by a large "P" or "B". See the pictures.
R/Side butt appears to have a well worn Cartouche, maybe a water mark. Again, see the pictures.
Underwood?? - If so what's the large "P" or "B" for??
TIA - Mike Haas