.22 Long is a variety of .22 caliber (5.6 mm) rimfire ammunition. The .22 Long is the second-oldest of the surviving rimfire cartridges, dating back to 1871, when it was loaded with a 29 grain (1.9 g) bullet and 5 grains (0.32 g) of black powder, 25% more than the .22 Short it was based on. It was designed for use in revolvers, but was soon chambered in rifles as well, in which it gained a strong reputation as a small game cartridge, and sold very well.
In 1887 the .22 Long case was combined with the heavier 40 grain (2.6 g) bullet of the .22 Extra Long of 1880 to produce the .22 Long Rifle giving a longer overall length, a higher muzzle energy and superior performance as a hunting and target round, rendering the .22 Long and .22 Extra Long obsolete. For a time there was a considerable price difference between the .22 Long and .22 Long Rifle, and the .22 Long held on with budget-minded shooters until the price advantage finally disappeared. No new firearms are designed specifically to use .22 Long and the largest three producers of .22 Long ammunition ceased production (although it continues to be made by CCI, Aguila, and others). Many firearms designed for the .22 Long Rifle will chamber and fire the shorter round, though the .22 Long generally does not generate sufficient energy to operate semi-automatic guns. The one prominent survivor of the .22 Long is the .22 CB Long, a long-cased version of the .22 CB.
While the original .22 Long loading used the same powder charge as the .22 Long Rifle, the .22 Long bullet was significantly lighter, and the combination did not result in higher velocities for the .22 Long when fired from a rifle. The large barrel volume to chamber volume ratio of a .22 rimfire rifle means that the powder gasses have expanded as far as they can well before the bullet reaches the muzzle of a normal length rifle barrel, and the light .22 Long bullet has less inertia than the .22 Long Rifle. This means that the .22 Long bullet (and to a lesser extent the .22 Long Rifle in most loadings) actually slows down significantly before it exits the barrel. For those working on a farm, or those who only hunted squirrel or cottontail, the shortfallings of the .22 Long when compared to the Long Rifle, were of little concern. Often the lower report, and less penetration were actually desired.
Since the .22 Long Rifle performs as well in a short handgun barrel as the .22 Long and outperforms it significantly in a long rifle barrel, the development of the .22 Long Rifle assured the .22 Long's path to obsolescence.
Descendants of the .22 Long still live on. Modern Hypervelocity loadings of the .22 Long Rifle use bullets as light as 30 grains (1.9 g), and modern blends of powder to make full use of a rifle barrel to generate velocities far higher than normal loads, and chamber pressures high enough to cycle semi-automatic firearms reliably. The most well known of these is the CCI Stinger, which actually goes so far as to stretch the case length slightly, so that with the short, light bullet, the overall length is still within the max overall length for the .22 Long Rifle.
The .22 Long is still produced as it survived the change over to smokeless powders. CCI currently loads a high-velocity .22 Long with a MV of 1215 fps and a ME of 95 ft. lbs.