(A.)
.
Due to the demand for varmint hunting and silhouette shooting, the .221 Remington Fireball cartridge was introduced
by Remington in 1963 for the (then new) "space style futuristic" Remington XP-100 Pistol (now an obsolete firearm).
The cartridge is based on a shortened 222 Remington cartridge with a .22 caliber projectile, velocity of (up to)
2650 Feet per Second and(up to) 765 Foot Pounds per square inch of energy, "that is over the 357 Magnum".
Some also consider this a rifle cartridge.
  
.221 Remington Fireball
Current Pistol & Rifle Cartridge Section
.
.