The .22 Hornet or 5.6×35mmR is a varminting, small-game hunting, survival and competition centerfire rifle cartridge commercially introduced in 1930. It is considerably more powerful than the rimfire .22 WMR and the .17 HMR, achieving higher velocity with a bullet twice the weight of the .17 HMR bullet. The Hornet also differs very significantly from these in that being a centerfire cartridge makes it reloadable, and thus much more versatile. It was the smallest commercially available .22 caliber centerfire cartridge until the introduction of the FN 5.7×28mm.
The .22 Hornet fills the gap between such popular varmint/predator cartridges as the .22 WMR and the .223 Remington. In regard to muzzle velocity, muzzle energy and noise, it is well suited to vermin and predator control in relatively built-up areas.
Prior to the development of the modern .22 Hornet, there was a conceptually similar but physically different cartridge by the same name invented in the 1890s by Reuben Harwood (nicknamed “Iron Ramrod)”, sometimes called the “.22 Harwood Hornet” to avoid confusion, as the two rounds are not compatible. Harwood’s cartridge was formed by necking down .25-20 Single Shot brass to .22 caliber, and was initially loaded with black powder.
The modern .22 Hornet’s ancestry is generally attributed to experiments done in the 1920s using the black-powder .22 WCF at Springfield Armory. Winchester adopted what had so far been a wildcat cartridge in 1930, producing ammo for a cartridge for which no commercially made guns yet had been built. It was not until 1932 that any company began selling commercially made guns for the cartridge.
Wildcat variants of the .22 Hornet, such as the .22 K-Hornet (designed by Lysle Kilbourn) and .22 Ackley Improved Hornet, can boost bullet velocity and energy considerably above factory .22 Hornet levels, but performance still falls short of what is deer-legal in the Netherlands or the United Kingdom, although it is legal for deer in some other countries and some American states.
Factory ammunition is widely available from all major manufacturers, generally with bullets weighing 34, 35, 45, or 46 grains (2.2, 2.3, 2.9, or 3.0 g), with bullets invariably either hollow point or soft point. Muzzle velocity typically is in the 2,500 to 3,100 ft/s (760 to 940 m/s) range, and muzzle energy is just over 700 ft·lbf (950 J) for factory ammo fired from a rifle. Velocities and energies are less when Hornet ammunition is fired from short-barreled firearms.
Published handload data from major handloading-product companies shows how versatile the .22 Hornet can be. According to the Hodgdon Powder Company reloading data, the heavier bullets show a serious affinity for Lil’Gun smokeless powder to produce much higher velocities than other powder with heavy bullets in this small case.