Craig Boddington was the senior contributing editor of our modern gun and ammunition caliber dictionary. Craig was involved in the development and testing of many of these and writes from first hand experience. This dictionary was written exclusively for Wholesale Hunter with unique information found nowhere else.
GUN CALIBER DICTIONARY
Rimfire
5mm Remington
The 5mm Remington (5mm Remington Rimfire Magnum) is a .20-caliber (.2045-inch) rimfire cartridge introduced by Remington in 1970. Based on a blank power tool cartridge case, its rim diameter of .3252-inch is larger than the 22 WMR case, so manufacturers other than Remington were reluctant to adopt it. Performance is very good, with a 38-grain bullet at 2105 fps...this slightly exceeds the 22 WMR, which was probably Remington's goal, but it was not popular and ammunition was unavailable for many years until CBC brought it back. — Craig Boddington