This is the Centerfire conversion of the 5mm Remington Rimfire Magnum. There are at least two sources of rifle conversions and cases manufactures. Several bullet makers supply 5mm bullets now. New rifles are being built on TC Contender Frames. It is a really fun cartridge. There were about 50,000 Remigton Rifles and 30,000 TC barrel chambered for the 5mm Remington. This conversion gives new life to these firearms. Bullet weights in the 30- 40 grain range, 1900 to 2600 fps. Commercial reloading dies are available. 

This text is based on information from “Cartridges of the World”, Hodgdon reloading manual, the cartridge designer and/or own resources.