Measured in inches, a gun’s caliber represents the size of the ammunition that the weapon can fire safely without damaging the barrel or any internal components.
Here is an example:
A gun with .22 caliber means that its barrel is 0.22 inches wide when measured top to bottom or left to right. It also means you’ll only be able to use .22 caliber ammo with that gun.
For this reason, it is important to understand the different caliber types before purchasing your air gun.
Another reason the air rifle caliber is important is often, it indicates what you can do with these rifles. Certain types of ammunition are better suited for accuracy and target shooting whereas others work better for taking out game and hunting.
There are many different calibers available today. But for air rifles, the four most commonly used are the .177, .20, .22 and .25 calibers, with the .177 and .22 calibers being the most popular.
.177 Caliber Air Rifles
The .177 caliber is the most popular of the four major calibers. It is the smallest, lightest in weight, and least expensive and offers most variety. Rifles made in this caliber often produce the highest muzzle velocities reaching 1250 FPS at the top end with many settling around the 1000 FPS level.
The exit speed produced by the .177 cal allows it to achieve the flattest trajectories among the four mentioned types, meaning that it shoots the straightest giving users the benefit of better accuracy. This is why it is the type that’s used in target shooting competition and the Olympics.
While it excels in hitting targets, the high velocity mixed with the small surface area of the pellet’s head limits its use for hunting small-sized game. Often because of its high speeds, pellets tend to penetrate right through the animal without delivering enough impact power to incapacitate it. This results in a lot of suffering for the animal. For this reason, hunting with .177 cal air rifles often works better with heavier pellets since these are able to deliver enough power to take out the animal instantly.
.20 Caliber Air Rifles
The .20 caliber is a hybrid of the .177 and .22 taking some properties from the two. While some shooters swear by this caliber, the jury is still out on this one since it hasn’t been able to take off in terms of popularity compared to the .177 and .22.
What you get is a fairly flat trajectory similar to the .177 caliber and more impact power as you’ll see below with the .22 cal. Together you get more accuracy compared to the .22 caliber and more power when placed side by side with the .177.
Keep in mind that there will be fewer brands and models to select from if you choose to go with a .20 caliber air rifle. There just aren’t as many manufacturers that produce them.
.22 Caliber Air Rifles
Choice of hunters, .22 caliber rifle is among the most efficient in bringing down prey. Using larger pellets that are heavier, these rifles are able to transfer the most impact energy to its target. For the explanation, we go back to our Physics 101 classes which explain F=MxA. This equation which tells us force is equal to mass multiplied by acceleration applies here.
Since the 0.22-inch pellets have more mass than .177 and .20 caliber ammunition, the .22 caliber rifles have the ability to deliver the largest force of impact to take down different types of game. This making it appealing to hunters. Also, loading the larger pellets are much easier than trying to insert small ones especially if you’re out in the woods stalking your prey and light is sparse.
The compromise to the heavier pellets is it isn’t able to shoot as straight and reach as far as the two above. So with larger caliber guns, the focus turns to finding one with enough power to achieve high velocities in order to take advantage of the larger pellet mass.
.25 Caliber Air Rifles
Among the four types of calibers, this is the least purchased among the group. Often limited to serious hunters, their size allows them to take out the larger game since some models have the ability to attain 30 FPE (foot pounds of energy) or more.
Choosing the Right Caliber
Choosing the caliber is one of the first things to consider when buying an air rifle. Getting the right caliber will let you take full advantage of its ability allowing you to achieve the best results. On the other hand, wrong caliber selection often leads to frustration since it becomes more difficult to achieve what you want to do.