These days airgunners have an amazing choice in calibers- the old traditional .177 and .22, .20 caliber (as made famous by Sheriden), .25 (an old favorite resurrected in recent years, 9mm, 45, 50, and even larger. Which is right for you? For target shooters, the question is moot- .177 is the standard, and that’s that. For everyone else, it’s an open issue.
99% of the books and columns you read tell you that .22 is the preferred choice for hunting. Why, is unclear. “The bigger wound channel”, say some; “more shocking power”, say others, and there are plenty of stories told about a particular shot, but I doubt anyone has ever actually done a careful study of the matter. Truth be told, given the low power generated by most airguns, shot placement is far more important than caliber- at least when considering guns in the 10-18 foot-pound range. I’ve never had any trouble making quick kills on vermin or small game at 50 yards with my .177 caliber rifles.
I suspect the recommendation of .22 for hunting goes back to when there was no such thing as a 16 or 20 ft-lb air rifle in common use. Or perhaps it’s from our friends in Great Britain, and on the Continent, where guns generating over 12 ft-lbs are restricted or licensed as firearms. There, the extra diameter might- just might- have made some difference.
Today, though, I’d recommend that hunters choose a pellet weight based on velocity and energy levels. As noted in a previous article, you shoud always choose a pellet heavy enough to keep the velocity subsonic- that is, below 1000 fps. Up to 20 ft-lbs, there’s not a lot of reason to use anything but .177 pellets. Even at 20 ft-lbs you can find heavy pellets that have much higher sectional density than most any .22 pellet. You might consider also .20 caliber as you approach 20 ft-lbs, as the Crosman Premier .20 has the same mass as their .22- and much higher sectional density. Beeman pushed .20 cal as “the ideal caliber” for years, as they had exclusive rights to a lot of popular guns in .20 caliber, but until the .20 Premier appeared on the market I couldn’t see much sense in shooting .20 cal unless you had a Sheriden pump-up gun.
Above .20 ft-lbs, the .25s start becoming more attractive. I did a review of the Beeman Crow Magnum in .25 some years ago that convinced me of the place for that caliber, as the gun under test was producing close to 30 ft-lbs. When you get into the really big airgun calibers and high energies- like 40 ft-lbs and up- you’re starting to intrude into firearms energy levels, with very loud guns, and that’s where I’d personally switch to a .22 long rifle cartridge. Still, a lot of people like these big popguns, and makers like Dennis Quackenbush and Gary Barnes produce some beautiful guns. My own feeling is that the very high powered guns- Quackenbush makes a 500 ft-lb rifle- will eventually lead to BATF regulation of all airguns, and that will be the end of being able to shop for these by mail. But that’s another story.
What about plinkers? What’s the best caliber for plinking? I’d say .177, since that gives you the most shots per dollar. Of course, plinking is all about fun, whether it’s popping asprins with a .177 gun at 20 yards or knocking over steel targets at 100, so buy what makes you happy.