PRESTO M2 Paratrooper Black Wormgroove handles vintage switchblade knife

PRESTO M2 Black Wormgroove handles vintage switchblade knife. This knife was made by the George Schrade Knife Co of Bridgeport, CT sometime between 1940 and 1956. It measures 4 1/8" closed and 7 1/8" open with steel liners. The blade is nearly full with light patina, light scratches and some scattered peppering. The scales are in nice condition with something settled into the grooves that makes them look gray. I'm sure they could be cleaned out, but it's an interesting look. Has bail (staple) and green nylon cord. The knife works well with blade tip deep and centered, strong snap and good lockup with approx 1/8" up and down at the tip. Very likely military issue, but probably post WWII, though some believe that these were issued near the end of the war. VG+ condition.