The M1947 Johnson auto carbine was intended as a replacement for a .30 caliber semi-automatic rifle that was standard US service rifle during World War II, the Korean War, and a limited amount when?
M1947 Johnson auto carbine The M1947 Johnson auto carbine is a semi-automatic derivative of the M1941 Johnson machine gun. It was intended as a replacement of the M1 rifle but not accepted. The auto carbine never got past the prototype stage, only five of them ever being made.
.30-40 Krag The .30-40 Krag (also called .30 U.S., or .30 Army) was a cartridge developed in the early 1890s to provide the U.S. armed forces with a smokeless powder cartridge suited for use with modern small-bore repeating rifles to be selected in the 1892 small arm trials. Since the cartridge it was replacing was the .45-70 Government, the round was considered "small-bore" at the time. The design selected was ultimately the Krag–Jørgensen, formally adopted as the M1892 Springfield. It was also used in M1893 and later Gatling guns.