Some years ago, the big excitement was the new hypervelocity .22 ammunition, like the Stingers from CCI, which used lighter weight bullets (32gr rather than 40) and slower burning powder to get velocities of 1400fps or more out of rifle barrels. Three years ago, the shooting blogs were raving about something different- a new heavier, slower round from Mexican ammunition maker Aguila. At 60 grains, the Aguila projectiles were 50% heavier than the typical solid .22, and velocities were down around 950fps. Subsonic ammunition is nothing new; you can buy CCI 22 CB Long cartridges that come out of the barrel at a plodding 750fps and delivers a piddling 32 foot-pounds of energy. What's new is a subsonic round that delivers the same kind of energy as the hottest .22LR rounds- in this case, 120 ft-lbs. This caught the attention of hunters, who liked the idea of a quieter cartridge that didn't give up anything in the way of power, and fans of silencers, who saw a cartridge that would work especially well in silenced guns.
Aguila accomplished this, simply enough, by using a heavier bullet. Nothing unusual about that. What's unusual is how they did it. Compared to centerfire cartridges, .22LR cartridges are limited in the range of bullet sizes that can be used. Because of its black powder heritage, the .22LR uses what's called a "heeled" bullet. This means that the part of the bullet seated in the case is smaller than the nominal caliber, and because of that, doesn't engage the barrel's rifling. You can't extend the bullet forward of the case because the length of the cartridge must fall into a very narrow dimensional range.
Some historical perspective is called for at this point. Younger shooters may not be aware that not long ago there there were three common .22 cartridges: The Short, the Long, and the Long Rifle. .22 Short cartridges are rarely seen, as almost almost all .22 guns are designed around the LR these days. Its only real use in the last 50 years has been in rapid-fire competition guns (prior to 2004), where the low recoil of the Short made accurate rapid fire easier. The Long, which uses the bullet of the Short in the LR case, has been obsolete for decades, and never really filled any particular need.
What Aguilar did was to put a very long bullet in the Short case, resulting in a cartridge the same size as a standard .22LR. So how do they get enough powder in a tiny case? Simple: The .22 LR case is far bigger than it needs to be. Remember, it started as a black powder cartridge, and black powder is much bulkier than modern smokeless powders. The Short case has more than enough room for a full LR charge.
So how well does it work? Very well... with some caveats. Long bullets need more spin to stabilize them than do shorter bullets. I've read that a spin of at least 1 in 9" is required for good stabilization of this round, though that may be overly conservative. (A rate of 1 in 16: is typical in .22 rifles.) My personal experience has been mixed. I've seen good trajectories indoors at 50' ranges, but some keyholing at 25 yards in the one gun I tested these in outdoors.
These rounds won't reliably cycle all semiautomatic actions, though it's hard to predict what will work and what won't. My Bernardelli 60, which digests CCI Mini-Mags with no difficulty, regularly jammed on these. But a brand-new Beretta 21a with only 50 rounds through it had no problem at all cycling- not a single jam or FTF. YMMV, as we say on the net. One other caveat: This is the dirtiest, smokiest round I've ever fired. (For the reloaders out there, this is smokier than Original Bullseye.)
So what's it good for? Hunting, first of all. Trajectory is not as flat as you'll get with a high speed cartridge, but at typical small game ranges it's no problem. It's a lot quieter than most .22LRs, and it should have good energy transfer without the excessive destruction a .22HP might have on smaller game. I think it might also be a good minimal self-defense round when used in short barrel .22 pistols like the NAA mini revolvers, and a number of bloggers have suggested this. It's an interesting cartridge, and something that .22 fans can enjoy experimenting with.
Update: I tested it in a North American Arms .22 revolver, and discovered that firing resulted in setback of the fired case and jamming of the gun. A search of the web revealed that other shooters have experienced that as well. I suspect the short case doesn't grab the cylinder walls well. On the other hand, it feeds very reliably in my Beretta 21A Bobcat auto, a gun that tends to be picky about ammunition. Go figure.
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