Calibers

Monday, December 15, 2008

If you want to provoke a “spirited discussion” among airgunners, just raise the question: “Which caliber is best?” Pretty quick you’ll find yourself surrounded by enthusiasts, each passionately pleading the case of their favorite.

Right off, I’m going to defuse all that by saying there is no “best” caliber; there is only the caliber that works best for your intended purpose at the time. Right now, the four main calibers in airguns are .177, .20, .22 and .25. Further, I’m going to run the risk of annoying some big bore aficionados by saying that I regard calibers above .25 as really specialty items. Certainly large bore airguns have their uses and their proponents, but overall they are a small fraction of the four main calibers.

Having said that, here are some of the things you might want to think about regarding caliber.

Accuracy — Accuracy is everything as far as I’m concerned; it’s one of the main reasons I shoot airguns. Robert Buchanan, owner of Airguns of Arizona, put it very neatly: “If you miss, it doesn’t matter if you missed faster or with more power, you still missed!”

Now, here’s a trick question: what increases the odds of achieving high accuracy? Stumped? Here’s a hint – every airgun will have a particular pellet that it “likes” and will produce the best accuracy. As a result, having a wide spectrum of pellets from which to choose increases the odds of finding at least one pellet that will work well in your airgun.

So, if accuracy is your sole criterion, .177 would be the best caliber, because it offers the greatest variety of pellets. Twenty-two caliber would be close behind with the next best selection of pellets from which to choose.

Another thing to remember when considering accuracy is the range at which you plan to shoot. If you are competing in 10-meter air rifle or air pistol, the behavior of the pellet beyond 10 meters isn’t really a concern. But if you are trying to knock down field targets at 55 yards or clobber varmints at 90 yards, accuracy at long range is a clearly a factor.

Weight and weight within caliber – The lightest pellets (between 4 and 5 grains) available are .177, but it is rare to find a .177 pellet heavier than about 16 grains. By contrast, .25 caliber pellets are available as heavy as 34.9 grains and usually not lighter than 17.7 grains. To understand why this makes a difference, see the next item.

Speed and trajectory – Shot from the same airgun powerplant, a light pellet will generally fly faster than a heavy pellet. But at any given velocity, a heavier pellet will carry more energy down range and will usually retain it longer than a light pellet that was launched at the same initial speed. Because of these considerations, for a really fast, flat trajectory out to, say, 50 yards or so, you might want to select .177. But beyond that, you might want to go for a bigger caliber with heavier pellets. I have noticed, for example, that airgunners who are engaged in high-accuracy long-range shooting at 100 yards usually select .22 caliber.

Power and impact – Launched at equal velocities, a heavy pellet will typically deliver more foot-pounds of energy to the target than a light pellet. If you want hitting power and if velocity and accuracy are equal, chose the heaviest pellet and largest caliber.

Wound ballistics – Bigger pellets produce bigger holes, but smaller diameter pellets may penetrate deeper.

Availability – In local retail establishments, you’re likely to find .177 pellets are more readily available than any other caliber, with .22 coming in a close second. .20 pellets are rarely available in ordinary retail outlets, and I’ve never seen .25 caliber pellets available anywhere except for in an online airgun store. Airguns of Arizona tells me that the bulk of their pellet sales are split roughly equally between .177 and .22. They add that sales of .20 appear to be waning, while demand for .25 pellets is rising.

Til next time, aim true and shoot straight.

– Jock Elliott

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