Excerpt from CHUCKHAWKS.COM: Guns and Shooting Online; Motorcycles and Riding; Military History; Astronomy and Photography Online; Travel and Fishing Information Guide
"The .22 Winchester Rim Fire (WRF) is all but obsolete. It was designed for the Winchester Model 1890 pump action rifle and was later adapted to Remington and Stevens rifles as well as Colt Revolvers. Winchester .22 WRF loads used a flat point bullet.
Remington manufactured the cartridge, loaded it with a round nose bullet, and called it the .22 Remington Special. The two are actually the same cartridge and are completely interchangable.
I mention it here because Winchester .22 WRF ammo will fit in a .22 Magnum chamber, but not the reverse. The WRF fires a 45 grain, copper-plated, lead semi-wadcutter style bullet at a velocity of 1,320 fps and 175 ft. lbs. of energy at the muzzle of a 22" rifle barrel. The sectional density (SD) of the 45 grain WRF bullet is .128. It hits with noticeably more authority than the .22 LR. Winchester also offered a 40 grain hollow point bullet.
Because its case is slightly larger in diameter than a .22 LR case (as is the .22 Magnum), the WRF will not go into LR chambers. Like the .22 Magnum, the WRF uses standard .224" bullets (like most centerfire .22's), not .220" bullets like the Long Rifle.
It is actually quite a useful cartridge, as it hits harder than the .22 LR and is less expensive and less destructive than the .22 Magnum. Unfortunately, sales have diminished almost to the vanishing point and .22 WRF ammunition is no longer cataloged by Remington, although Winchester and CCI occasionally produce runs of .22 WRF ammo. Note that CCI warns against using their .22 WRF ammunition, which is loaded with a JHP bullet, in .22 WMR guns."
By Chuck Hawks