The level of power that can be generated with airguns depends on what type of airgun you’re talking about. Most of the inexpensive CO2 and pneumatics that are produced for the mass market plinkers generate from 4 to 12 fpe, while the big bores built by Quackenbush can generate over 500 – 600 fpe. And if that’s not enough oomph for you, there have been 20mm prototypes built by airgun tuner/designer Bob Dean which can put out well over a 1000 fpe!
As a general rule of thumb, even the most high powered springers and PCP production guns are much less powerful than firearms. While most CO2 airguns are fairly low powered by comparison to springers and PCPs, the Argentinean made Shark bulk filled CO2 rifles can produce around 15fpe. I believe that the most powerful CO2 gun on the market is the Sokol Carbine which puts out around 20 fpe. Springers usually generate around 16 – 20 fpe, though there are some very powerful models in .25 caliber manufactured by Webley and Scott that get up to 30 fpe, and in the RX2 gas ram version from Beeman the power is around 28 fpe. Many production pre-charged pneumatics can generate much higher energy levels, the Sumatra carbine gets up to 55 fpe and the Dragonslayer brings it in at around 190 fpe. The Sumatra has a feature I really like, which is adjustable power. I can dial it down for plinking or target shooting in my basement range, crank it up a bit when I head out to do pest control around a barn but don’t want to risk over penetration or punching a whole through the roof with a miss, then go full power when heading out for jackrabbits or larger quarry a greater distances. This effectively gives you three guns for three applications for the price of one.
You can also change the power in your pneumatic guns by fiddling with the hammer springs; a lighter spring will reduce the power and a heavier spring will increase it. In my DAQ .308 I use a light spring when shooting the light round ball for small and medium game, but switch over to a heavier spring when using a 120 grain cast bullet for bigger game. The tradeoff you make is that the shot count is reduced, with the heavy spring I get about four full power shots and with the lighter spring it jumps up to seven or eight shots.
What gun to use for what game is an interesting topic that is sure to get airgunners arguing, or at lest talking! My personal belief is that any .177 or .22 airgun that generates 12 fpe is appropriate for small game animals at 30 yards. If you’re going to push the distance another 10 yards I’d want something in the 14 to 16 fpe range. You have to remember that the energy level when your pellet finds its quarry will be lower than it was at the muzzle, and that the power diminishes more rapidly with smaller and lighter pellets. Some shooters that use their airguns for pest control, will opt for lower power 8-9 fpe guns because they shoot at closer range around barns and animal feed lots for instance, and want to make sure that they don’t damage animals or property with a missed or over penetrated shot. When you start to get up into what I consider medium sized airgun quarry such as raccoon or woodchucks I prefer a .22 or .25 putting out around 30 fpe. If I am going to shoot at longer distances for medium game, I will often use one of my larger bore airguns. When moving into the area of larger or harder to kill game, say coyote or bobcats I think a .308 caliber in the 150 fpe range is a good idea. And if the quarry is large and tough: deer, wild hogs, exotics, or African plains game, I think a large bore airgun that puts out at least a couple hundred FPE is the minimum, and I prefer a gun in the 300 fpe on up category. There is no doubt that you can kill an animal with a lower power gun than I’ve recommended, it has been done. That doesn’t make it a good idea, many deer have been killed with a .22 rimfire, but there is a reason it is not legal in most places, the chances of wounding or maiming an animal is high. There was a guy on television that shot a wild hog in the head with a .177 spring piston airgun, and was proud of it! That gun with the light pellet was putting out less than 15 fpe, a fraction of the energy a .22 rimfire generates. Yes he killed a pig on TV, I’ll bet he wounded a few first. And even if he did not it was because he was lucky. In my opinion, this type of stunt does more to damage the credibility of serious airgun hunting that any other thing I’ve seen. I’ll say the same thing to airgun hunters that is the guiding principle of firearm hunting …. Use enough gun.
What’s this 12 fpe thing in the UK?
It is somewhat ironic that in the United Kingdom, which is arguably the center of the airgunning universe and where many of the best PCP airguns originate, there is a limitation on the power of an airgun that can be owned without a fire arms certificate (FAC). Air rifles can not be over 12 fpe and air pistols can not be over 6 fpe. If a gun exceeds this limit and the person in possession of that gun does not have an FAC, heavy penalties up to big fines and a long prison sentences can result. This limit does allow enough power for small game hunting out to about thirty yards or so, but does not allow much margin of error. I believe this is one of the reasons that British airgun hunters are such sticklers when it comes to restricting their shot placement to their quarries head.
The reason that this limit was established in the first place seems to be a result of lobbying initiated from within the airgun manufacturing industry itself. The story goes, that at the time this regulation was passed the British airgun manufacturers were unable to produce guns that generated the power level of foreign imports. The tactic was to protect the market by enacting this arbitrary limit and provide a shield against technologically advanced offshore competition. Unfortunately once this type of restriction is in place the chances of having it repealed, especially in the current anti shooting climate, are slight. Some swear by this story while other say it is urban legend, but I’ve not heard any better explanation and the unfortunate bottom line is the limit exists. While it is eminently possible to hunt at 12 fpe, my personal preference is to have at least 16 fpe as I have seen a pretty significant difference in the ability to achieve clean kills with just this 4 fpe jump. From a practical standpoint, if you buy a gun from Britain make sure it is or can be tuned up.