Hunting Airgun: Power Requirements

One of the most common questions asked by hunters when they start to use airguns is “how much power do I need to kill a rabbit, a coyote, a deer? Conscientious hunters want to make sure they are using enough gun to cleanly drop their prey. Hunters should try for the quickest, cleanest, and most effective kill. When the trigger is squeezed it should be for the highest percentage shot, be that a head or a chest shot. I’ve heard some say “you should always use a head shot when squirrel or rabbit hunting”, but I believe it’s situational. When I hunt squirrels in spring my preference is head shots, because the dense foliage on the trees allows me to get closer and in these conditions a chest shot might leave them with enough gas in the tank to get lost in the leaves and branches. But I’ll take the chest shot on the same quarry in the same woods in winter, when there is less cover on the trees and less chance of losing an animal even if it runs a few yards.

Power delivered on target is not the limiting factor in most cases, rather it’s the ability to put the target right on target.

I’ve heard some maintain a headshot is more humane, and while I would never inflict unnecessary pain on an animal, the fact that it runs a few yards after a chest shot doesn’t mean its feeling more or less pain. Remember that the typical death of a squirrel or rabbit in the wild is generally a lot less pleasant than getting shot, head or chest. The pertinent question one should ask; is there a valid reason for shooting the animal? These reasons can be for food, to control populations, to eradicate populations, and I’ll go out on a limb and say trophy hunting. The hunters motivation to hunt is an individual issue, the regulations are based on if it make sense from a wildlife management perspective.

Circling back to the question of power; the statement that a hunter wants to make the quickest, cleanest, and most effective kill means that they need a gun generating enough power and poking a big enough hole to meet these objectives. In North America we’re a firearm culture and we’ve been raised to believe more power is better. Because of the prevalence of firearms, airguns and their capabilities have been overshadowed, so their validity as hunting weapons has been suspect. The truth of the matter is that airguns can put out a lot more power than has been generally attributed to them,  and that at the same time it takes a lot less power to cleanly take game than many people realize. In this article I’ll take a look at some of the rules of thumb I use in my airgun hunting to ensure that I am using a gun appropriate to the game and situations I expect to encounter.

What Energy Levels do Airguns Produce?

Most of the conventional .177, .20, and .22 spring piston rifles on the market today will generate between 10 -20 fpe of energy, with outliers in either direction. A few, especially the big .25 magnums can go considerably higher tracking up into the 30 fpe range. That is enough power to take anything up to a raccoon size animal if the correct shot placement, pellet selection, and range is adhered to. But as a rule, springers can be difficult to master and shoot accurately. Both the .22 caliber 16 fpe and .25 caliber 30 fpe guns will anchor a raccoon at 30 yards with a perfect headshot, but it can be harder to get the shot placement with the more powerful gun. We’ll come back to the accuracy vs. power discussion a bit further on.

When you get into precharged pneumatic rifles the range of energy levels produced really opens up, my guns go from a UK spec’d 12 fpe Webley Raider to a 550 fpe .457 Quackenbush. As a rule, most guns in the .177 and .22 calibers are in the 16 – 35 fpe range, the .25 in the 35 – 60 fpe range, the mid bores (.303 – .357) from the 75 fpe to 200 fpe, and the big bores (.40 – .50) anywhere from 200 fpe to 600 fpe. Again there are outliers in all of these, especially when we start look at tuned, modified, and custom guns, but the above gives a reasonable overview.

So there is a wide range of velocities and energy levels that today’s airguns can produce. But this is just one variable in what guns are best for a specific hunting scenario. To keep this discussion manageable, I’m going to limit it to small game and predator hunting, as big game is more of a niche segment of airgun hunting.

Hunting airguns benchmarked against the .22 rimfire

Probably like most guys of my age that grew up in the USA, the .22 rimfire was the basis of my development as a hunter. As a kid I carried a number of rimfire rifles through the mountains, desert and coastal hills of (a very different) Southern California. My California was one of orange groves and bean fields, rolling hills, and undeveloped tracts of land where a kid could walk along with his rifle over his shoulder, waving to cars as they drove by without rousing the local SWAT team. I took countless ground squirrels, rabbits, crows, quail, raccoons, and the occasional coyote with these guns. I dropped a lot of game and I lost some, and really came to understand that a well-placed shot was the key factor to success.

A .22 rimfire typically pushes a 40 grain bullet at 1050 fps, generating 100 fpe. So if we look at the energy delivered by a 16 grain .22 pellet moving at 900 fps and generating 28 fpe, and consider the fact that the .22 rimfire didn’t always do the job, we might be forgiven for discounting the air rifle out of hand. However either of these projectiles would anchor a big jackrabbit on the spot at 50 yards with a well-placed brain or a heart shot. In my experience the average air rifle is more accurate than the average rimfire, so I’m more consistently able to make a “perfect” shot with one of my air rifles. On the other hand, the rimfires heavier bullet and much higher velocity (especially at 50 yards) means that even a less than perfect hit will probably kill the rabbit.

The crux of the matter is just this, while energy dumped on target is important, it is the ability to place the shot on target with precision that is critical. What I mean is that a gun delivering a pellet to a jackrabbit’s heart at 10 fpe is not going to make it any more dead than hitting it with 25 fpe. So my maxim is that” its accuracy first power second”. This of course is making the assumption that a minimum power level is achieved.

The British experience has proven this to be the case, in a country where by far and away most of the guns are under the legal limit of 12 fpe (without a firearms certificate),  our cousins across the pond have been very successful in hunting rabbits, squirrels, crows, and  pigeons in huge numbers.

I believe that all things considered, more power is better, it allows you to reach out further, gives more latitude in shot selection, and lets you hunt the larger bodied animals we have in North America. There are times however, when hunting around farms, buildings, livestock etc. that a lower powered gun might be preferable. I was out doing a pest control pigeon shoot inside and around a barn, and opted for a low power setting on my pcp of 10 fpe (you have to love the adjustable powered guns). These pest birds went down cleanly, there was no over penetration on hits, and the couple of misses that hit the tin roof didn’t cause any damage.

The influence of range as it affects the power required to kill quarry is usually less of an issue than the shooters ability to place the shot accurately at longer distances. Because of the lower velocities obtained with most airguns, which also shed velocity rapidly due to the relatively poor ballistic coefficient of most pellets, makes dealing with trajectory more of an issue than experienced with a rimfire. This is not to say you can’t reach out with an airgun, I’ve routinely taken prairie dog at about 100 yards with higher powered .22 and .25 caliber guns. However you’re ability to place the pellet exactly where you want it will limit your range before the drop in killing power does.