The .38 rimfire / 9.5x22mmRF refers to a family of cartridges that have been in service in the United States since the mid-19th century.

Much like the smaller .32 rimfire, the rounds were originally manufactured loaded with black powder.

The .38 rimfire cartridge was a common round for many antique revolvers and rifles from the 1870s to the early 1900s.

Production in the United States of rimfire calibers larger than .22 ceased upon the country's entry into World War II and was never resumed again by any of the major manufacturers.

While there were a few different rifles produced for the .38 extra long cartridge and a few rolling block, falling block, and bolt-action rifles had smoothbore barrels which had a slight choke which enabled it to shoot the .38 RF shotshells, which was good for hunting small game at close ranges.