 In February 1944, the M1A1 reached a low price of $45 each, including accessories and spare parts, although the difference in price between the M1 and M1A1 was only $0.06.By the end of the war, the M1A1 was replaced with the even lower-cost M3 (commonly called the "Grease Gun").The Model 1927 was the open bolt semi-automatic version of the M1921.