Manufactured by the Union Switch & Signal Co. (US&S) in 1943, this pistol has a bright blue DuLite finish and is hand-stamped "U S & S/E X P" in two lines on the right side of the of the frame. This pistol is one of approximately 100 pistols manufactured by US&S using preproduction slides, receivers and other components that were later assembled and presented to company officers and employees. There is little documentation on the US&S "EXP" marked pistols. The left side of the slide is roll-stamped with the standard "USS" logo followed by "U.S. & S. Co./SWISSVALE, PA. U.S.A." in two lines. The right side of the frame was hand-stamped "U S & S/E X P" in two lines after the frame was finished. This marking lacks the hand-stamped serial number found on most of the US&S "EXP" marked pistols. There are no "P" proofmarks on the slide and frame. The left side of the frame is not stamped with the "R.C.D." final inspection mark found on regular production US&S pistols. This pistol has the typical US&S stamped trigger, narrow hammer with borderless knurled spur, checkered slide stop, fine checkered mainspring housing, and checkered safety lock. The barrel has the same high polish blue finish as the other components with the High Standard "HS" markings stamped on the right side of the lug and a block "P" proof stamped on the left side. The Keys Fiber Company brown plastic checkered grips are the early style without escutcheon rings around the screw holes. The inside of the grips have interior reinforcing ribs and are stamped with a five-pointed star and single-digit mold number. The dull blue, flat base magazine was manufactured by the M.S. Little Co. and is stamped with the "L" code mark on the top of the floor plate lip. The US&S "EXP" marked pistols are scarce and very desirable. The pistol is pictured in Scott Meadows book "U.S. Military Automatic Pistols, 1920-1945, Vol. II" on the top of page 151. Previously from the Miguel Hughes collection.