Introducing the .22 Long Rifle to a bunch of rifle cranks makes about as much sense as asking Vin Scully if he's ever heard of Sandy Koufax, so I'll keep this brief. Smith & Wesson produced the first .22 rimfire cartridge, which it chambered in its First Model revolver in 1857. Fourteen years later the Smith & Wesson case was extended 0.192 inch so it could hold an extra grain of powder, and thus the ".22 Short" and ".22 Long" names were adopted.
A .22 Extra Long followed, but it wasn't particularly accurate. Finally, in 1887, the ballisticians at J. Stevens Arms & Tool plugged a 40-grain bullet from the .22 Extra Long into a .22 Long case and, voila, the cartridge we all know and love as the .22 Long Rifle came to pass.
Fast-forward seven decades. In the late 1950s, Winchester released a number of new rifle cartridges, and one of those was the .22 Win. Mag. Rimfire, also known as the .22 WMR or simply the .22 Mag. Its parent case was the .22 WRF the company launched in 1890, and Winchester lengthened that case to 1.055 inches.
The .22 Mag.'s case was considerably longer than the .613-inch .22 Long Rifle's and wider as well, so it offered a significant power upgrade. With 40-grain bullets the .22 WMR leaves a rifle barrel traveling at 1,800 fps, whereas .22 LR ammo zips along around 1,200 fps. This brings a significant difference in muzzle energy for the .22 Mag.—300 or more foot-pounds at the muzzle for the WMR versus about 140 ft.-lbs. for the Long Rifle.
In addition, there is a much wider selection of bullet constructions for the .22 WMR, with several jacketed hollowpoint offerings for serious small game and varmint hunters. Most .22 LR loads, even hunting loads, are simply copper-plated lead. That's fine for small game at modest ranges, but if you're considering reaching out a bit—perhaps 100 yards or more—on varmints of any size, then the .22 WMR is the clear winner. And it's a far better option for coyote hunting, although its capabilities are still limited as compared to the .22 centerfires.
The .22 WMR has also been branded as a self-defense round, and while it's hard to argue for any rimfire as the ideal personal protection cartridge, the .22 WMR's boost in energy and the availability of jacketed defense ammo like Hornady's 45 grain Critical Defense load and Winchester's 40-grain PDX-1 make the WMR the better defensive option of the two cartridges.
But the rimfire arms race isn't all about speed and power. If your ambitions include plinking cans and targets in the backyard and swatting small game and vermin at close range, the .22 LR performs just fine and ammunition costs considerably less.
On average, you'll have to spend between a nickel and a dime each time you fire your .22 LR, and the cost will be closer to a quarter with each pull of the .22 WMR trigger. If you don't shoot a lot, that's not significant, but over time the price of ownership of a .22 WMR is higher than a .22 LR.
There have been thousands of .22 LR rifles produced over the years, and ammo is once again on every hardware store shelf. Whether you like lever actions, pumps, semiautos, single-shots or bolt guns, you'll be able to find a .22 LR that suits you. While .22 WMR rifles aren't rare or particularly expensive, there are still more .22 LRs available.
Recoil is negligible with both rounds, but noise levels are significantly higher with the .22 WMR. In short, the .22 WMR offers a boost in power for those who want to shoot varmints and predators or defend themselves with a rimfire. If you're simply looking for a target or training rifle or plan on hunting small game like rabbits and squirrels at 50 yards or less, then the ubiquitous, mild-mannered .22 LR is impossible to beat.