.22 Hornet

The .22 Hornet is a black-powder cartridge that was quietly modernised into a smokeless one. Townsend Whelen and G. L. Wotkyns worked it up at Springfield Armory in the 1920s out of the obsolete .22 WCF, and Winchester put it on sale in 1930 — for two years before anybody sold a rifle chambered for it, which is an unusual order of events for a commercial cartridge.

Its shape is the giveaway. The case tapers 1.43 mm from a base of 7.59 mm down to a neck of 6.16 mm and meets a shoulder so shallow that it barely reads as one, because that is what a case designed to be filled with black powder and extracted from a single-shot rifle looks like. The rim projects, so the round headspaces on the rim rather than the shoulder and works in break-action, falling-block and single-shot rifles that would need a controlled-feed bolt to handle a rimless case. What Winchester changed was the loading and the bullet — a jacketed 0.224-inch bullet at smokeless pressures, taking a case originally rated in the hundreds of feet per second up to around 900 m/s with a 35-grain bullet.

That combination gives it a peculiar niche. It is the smallest centrefire round with which the American industry ever bothered — nothing smaller existed commercially until the 5.7x28mm — and it sits between the .22 WMR and the .223 Remington in every respect including report, which is why it persisted for pest control near buildings after faster .22 centrefires had displaced it everywhere else. It also went to war in a small way, in USAAF aircrew survival rifles. Both of the two well-known wildcats on the case, the .22 K-Hornet and the Ackley Improved version, work by blowing the taper out and steepening that shallow shoulder.

Gaps on this page: the four loads recorded here are the encyclopedia’s ballistics table, which names Hodgdon Powder Company as its source — reloading data rather than a factory datasheet — and states a single 24-inch test barrel for every row. No ballistic coefficient is published beside any of them. The bullet diameter is the C.I.P. cartridge maximum; rifles built before the standard settled may be bored 0.001 in smaller, and no source gives a date at which that stopped.