The magazine release is marked “SW” which is a Standard Products mark (page 100-101). The hammer is marked “SW” which is a Standard Products mark (page 89 – 90). The left rear of the trigger group is marked “ST” which is a Standard Products mark (page 78). Underwood supplied dated barrels to Standard Products for assembly (pages 50 of Craig Riesch’s book, U.S. The top of the barrel is marked “UNDERWOOD / 2-44 / flaming bomb” an “P”. The left side of the receiver is marked “1 5 B” below the wood line. CARBINE / CAL.30 M1” on the front and “STD. Markings: There is no visible import mark. Barrel Date: 2-44Īction Type: Semi Auto, Detachable Magazine. Year of Manufacture: April to June, 1944 (page 31 of Scott Duff’s book, The M1 Carbine Owner’s Guide).