The .22 Accelerator is a special loading of the .30-30, .308, and .30-06 cartridges that is manufactured by Remington.
[1] It consists of a sub-caliber 0.224-inch (5.7 mm) diameter bullet, held in a .30-caliber 7-grain (0.45 g) six-fingered plastic sabot with a hollowed base.
The bullet separates from the sabot approximately 14 inches (360 mm) from the muzzle.
The cartridge allows for using a large-caliber rifle for varmint shooting, although the accuracy is somewhat diminished.
[1] The advantage, however, is the extremely high muzzle velocity from factory-loaded ammunition.