Remington's 5mm Rimfire Magnum

Shooting a Classic

- Layne Simpson

Layne in the field with a T/C Contender single-shot rifle chambered for the 5mm Rimfire Magnum.

The 5mm Rimfire Magnum was at the very top of the really big news list during the Remington writer's seminar of 1968. A maximum average chamber pressure of 33,000 psi pushed a 38-grain Power-Lokt, hollowpoint bullet measuring .2045 inch in diameter to a muzzle velocity of 2,100 feet per second (fps). In comparison, Winchester's .22 WMR, which had arrived on the scene 11 years earlier, was loaded with a 40-grain bullet at 22,000 psi for 2,000 fps. Residual energy at 100 yards was 217 foot-pounds for the 5mm Magnum and 170 foot-pounds for the .22 WMR.

The bottleneck case of the 5mm Magnum was a bit shorter than the .22 WMR case but a body diameter about 10 percent larger made room for more powder. Rim diameter was close to 11 percent larger. Due to a higher ballistic coefficient, the Remington bullet shot a bit flatter, although it was not enough to matter at the effective ranges of both cartridges. More important in the field, 5mm Magnum residual velocity at that distance was more than 200 fps higher for increased bullet expansion. The bullet was produced by forming a soft lead core and then giving it a thin jacket by the electroplating process. Five longitudinal serrations in its nose, along with the hollow cavity promoted rapid expansion on any varmint unlucky enough to receive it.

Aguila 30-grain Remington 5mm Rimfire Magnum ammunition exceeded 2,100 fps from the 10-inch barrel of a T/C Contender pistol, and 2,300 fps from the 23-inch barrel of a T/C Contender rifle.