The first M-25s were produced from kits imported from the United States and the main difference between the later M-25 and the R-1820-F3 is the use of metric components. 13,888 M-25s were produced in the USSR at factories in Perm and Kazan. There were a number of sub variants which differed from the original M-25 in that they had reduction gears, rather than direct drive. Performance was similar to the equivalent Wright engines. The M-25 was later developed into the ASh-62 and was later used as a pattern for the M-70. The M-70 being a twin-row 18 cylinder engine, eventually developed into the ASh-73 which powered the Tupolev Tu-4, a reverse engineered copy of the Boeing B-29.