In 1969, Remington Arms Company designed and introduced the 5mm Remington Rimfire Magnum cartridge, chambered in two of their bolt action rifles – the Model 591 and Model 592. The company ended production in 1973, after having produced about 52,000 rifles. No other major manufacturer ever produced any rifles chambered in 5mm RMR.
In 2008, Taurus International announced that they would manufacture one of their Tracker series handguns chambered for the 5mm RMR. They marketed the nine-shot double action revolver to varmint shooters. At that time, Aguila Ammunition simultaneously announced that they would start producing 5mm RMR ammo. Taurus has not yet released the Tracker for sale, nor has a release date been announced, but it is fairly easy to find the Aguila ammunition.
The case for the 5mm RMR was an improved rimmed bottleneck design based on the .22 Winchester Magnum Rimfire. The bullet is 5.2mm in diameter, it weighs 30 grains, muzzle velocities reach between 2,300 and 2,400 feet per second firing a JHP bullet, and muzzle energy is approximately 350 foot pounds. The cartridge enjoys a positive reputation for its accuracy, but is appreciated even more for its ability to terminate small game and varmints.
The 5mm RMR hits harder and flies faster than the .17 HMR and .22 WMR, and shoots flatter than the .22 WMR. So it remains a mystery why this cartridge experienced so little success in the market. Some firearms authorities say the design and performance of the 5mm RMR were ahead of their time, and the shooting community never fully appreciated the real potential of the cartridge. The 5mm RMR today still maintains a foothold among a dedicated group of varmint hunters, as the Remington rifles produced for the cartridge about 40 years ago are still shooting and serving their owners well.