Rifles and pistols chambered for .22 Long Rifle can safely chamber and fire the following cartridges:
- .22 BB Cap (mostly unavailable)
- .22 CB Cap (available in both Short and Long cases)
- .22 Short
- .22 Long (No longer very common)
- .22 Long Rifle in both standard velocity (subsonic) and high-speed.
- .22 LR Shot (I haven't tried these so won't comment further.)
There are "hyper velocity" .22 LRs like CCI Stingers and Velocitors, and Remington Yellow Jackets and Vipers. Conversely, there are standard velocity rounds intended for hunting, e.g., CCI Subsonic HPs and Aguila Sniper Subsonics. The latter is a .22 LR length round, but loaded with a heavy 60 grain bullet in a .22 Short case.
Most .22 LR semiautos will function only with Long Rifles. The other rounds won't have enough power to function the action. The Remington Model 572 is a notable exception, being designed to function with Shorts, Longs, or Long Rifles. Sometimes, manually operated repeaters won't function with anything other than LRs either. However, they'll work as a single shot if you load the round directly into the chamber.
Standard velocity rounds, especially hollowpoints or solids which have been flatnosed, work well for small game hunting with good shot placement. They are quieter than high speed loads and often are more accurate.
For controlling vermin larger than rats, high speed or hyper velocity hollowpoints work better than standard velocity loads, except for the Aguila Sniper Subsonics. .22 LR can be used on varmints up to the size of woodchucks and racoons, but shot placement is key. I've seen a rabid raccoon that weighed about 15 lbs absorb over a half dozen high speed hollowpoints PLUS 5 standard velocity solids without expiring. These were all hits in the chest cavity from no more than 10 - 15 yards. A shot through the brain was required to finally kill it.
Small vermin such as rats can be taken care of with standard velocity loads, .22 Shorts, or even CB Caps. I have a couple of boxes of CCI .22 CB Longs that I keep around in case this is necessary. Fired from a rifle, they are about as noisy as an airgun. In other words, pretty darn quiet.
While it's better than nothing, a .22 is not a good choice for defense against people. It simply doesn't have enough bullet mass to reliably stop an aggressor. See my comments about the rabid raccoon above. The light weight, relatively low velocity bullets don't pack enough punch to reliabily penetrate to an attacker's vitals and cause enough damage to force him to stop. That said, high velocity solids would be my choice if I needed to use a .22 for defense; the specific load I'd want would be CCI Mini Mag solids for both its relatively good penetration and CCI's high quality. The only time I'd recommend a .22 for a defensive gun would be for someone who can't handle anything bigger. But, if push came to shove in a worst case scenario, and a child needed to help defend the homestead, then something like a 10/22 with a full load of Mini Mags beats a sharp stick.
The best accuracy will almost always be obtained with some kind of .22 LR ammo. When fired in a LR chamber, bullets from .22 Shorts have a long jump from the case to the rifling, which hurts accuracy. The rounds that a given gun will shoot the most accurately can only be determined by trying a variety of ammo. I recommend buying a 50 round box or two of several kinds of ammo and shooting them at a paper target from a bench, to see what the gun likes best. Shoot at least a couple of targets, at least one of them at 50 yards, to see how individual loads work at a distance.
Shooting for accuracy out to 50 yards is especially important with the Aguila Sniper Subsonics. The heavy 60 grain bullets pack a wallop but are often unstable in .22 rifles with the standard 1-in-16" rifling twist. Since they are somewhat expensive, it's a good idea to test a box to see if they'll shoot acceptably in your gun before acquiring a substantial quantity.
In my experience, the most uniformly accurate and high quality .22 LR ammo (other than specialty target loads like Eley Tenex) is made by CCI. I used to favor Winchester PowerPoints, but had several duds in one brick. I've never had a CCI .22 fail to go off. CCI Mini Mags and Subsonic Hollowpoints function well and shoot accurately in all of the .22s in which I've tried them, including a Ruger 10/22. Savage Mark IIGL, S&W Model 18, Ruger Single Six, and a Winchester 9422.
I recommend storing rimfire ammo in an airtight ammo can, either a GI surplus can or something like an MTM Sportsman's Dry Box. Rimfire ammo is not as well sealed against moisture penetration as centerfire ammo, and if the ammo gets wet or is exposed to humidity for a long time it may go bad.
Hopefully this post has given you some food for thought regarding .22 rimfire ammunition selection. Please share your insights in the comments.