As a well established ammunition caliber, the .22 Long Rifle is the most common caliber in the world today in terms of units sold. Commonly referred to as just .22LR or 22LR, the .22 Long Rifle caliber has seen use in many rifles, pistols, revolvers, and shotguns. The popular round was developed by J. Stevens Arms & Tool Company in 1887. This was done by merging the casing of the .22 Long and the bullet of the .22 Extra Long.