22 Long Rifle

The .22 Long Rifle rimfire (5.6×15mmR – metric designation) cartridge is a long-established variety of ammunition, and in terms of units sold is still by far the most common in the world today.

The cartridge is often referred to simply as .22 LR and various rifles, pistols, revolvers, and even some smoothbore shotguns have been manufactured in this caliber. The .22 Long Rifle and related cartridges (.22 Short, .22 Long, and .22 Extra Long) use a heeled bullet, which means that the bullet is the same diameter as the case, and has a narrower "heel" portion that fits in the case