Which is the best Caliber for Airgun Hunting?

If you asked 10 airgun hunters which is the best caliber for airgun hunting, you’ll get a dozen different opinions and perhaps a bloody nose after the heated argument!  It’s an age old debate with no end in sight.  The truth, however, is there is no right or wrong as every caliber can work for hunting but they all have distinct niches in which they excel.  Let me take you through the four most common airgun calibers.

Muzzle Energy

Before we actually launch into what calibers you should look at, as hunters we need to understand a bit about airgun ballistics and how it applies to the game we hunt.  Kinectic Energy is a measurement of the velocity and mass of an object in motion.  As Kinetic Energy for airguns is usually determined by measuring pellet velocity near the gun, we normally call it Muzzle Energy.

A simple formula that can be used to determine Muzzle Energy is : Velocity (FPS) X Velocity (FPS) X Pellet Weight (Grains) / 450,240 = Foot Pounds of Energy (Ft/Lbs or FPE).

In my opinion the measurement of the energy tells me much more of how a gun will perform for hunting than just the muzzle velocity.

.177 Caliber/4.5mm

The smaller .177 is a terrific caliber to tackle light bodied animals like this European Starling taken with a Remington Genesis at 40 yards.

By far, the venerable .177 caliber is the most common and popular airgun caliber.  It’s extremely cheap to shoot and is available just about anywhere you can buy an airgun.  The .177 caliber can work well for airgun hunting but there are a couple limitations to understand if you decide to spring for it.

This small caliber comes in a variety of pellet weights ranging from 7.0 to 20.0 Grains with 8.0 to 10.5 Grain being the most common and useful for hunting.  Because the pellets are so light air rifles are able to shoot them at higher speeds; which translates into a flatter pellet trajectory.  This is great for folks who aren’t quite comfortable with the idea of holding over/under. However it does come at the cost of the pellets not being able to handle wind as easily.

It should be noted as well that most .177 pellet designs are not built to exceed supersonic velocities before they tumble and yaw in flight.  The Speed of Sound is about 1,100 FPS. So if you’re experiencing some accuracy issues with one of the popular “1,200 FPS” air rifles I would recommend trying a heavier pellet to gain stabilization (the gun will also be quieter).

I have found that 20 Ft/Lbs is about as hard as you want to push .177 caliber.

.22 Caliber/5.5mm

The .22 cal has been my go-to squirrel nabbing caliber for many years.  It’s a great caliber to use in moderately powered spring rifles like this RWS 94.

Easily as popular as the .177 caliber these days, the .22 caliber has been a favorite of mine for many years.  This caliber comes in weight ranges from 12 to 30 Grains and pellets are as easy to find as .177.

I find that the .22 caliber excels in hunting applications due to the increased pellet weights and large overall pellet diameter.  The large pellets create larger wound channels in the animal as well as deliver considerably more terminal energy.  I’ve found that the pellets are much easier to handle and load into the rifle than for .177 caliber.

Due to the pellet weight increase the .22 caliber is able to buck the wind better, allowing you take ethical shots at longer distances.  This caliber tends to perform best at Muzzle Energies of 15-35 Ft/Lbs.

.20 caliber/5mm

Shot placement is far more important for airgun hunting than high velocity.  This fat groundhog was put down with a single .20 caliber JSB pellet to the head at 33 yards at around 890 FPS.

The .20 caliber is certainly one of the most overlooked calibers in the airgun niche and without good reason either!  I will admit that I’m a bit of a .20 caliber fanatic, but there a few reasons why I simply adore this sizing.

Essentially the 5mm is the happy middle ground between the .177 and .22 calibers.  It offers a similar flat trajectory to the .177 with the stopping power of the .22.  With these qualities the .20 caliber excels at target shooting and I’ve observed an almost magical performance on small game dropping animals as effectively as the .22 caliber.  Pellet weights range from 10 to 14.3 Grains.

Unfortunately since this caliber isn’t as popular you will find that not as many rifles are offered in .20 caliber nor as many varieties of pellets.  The pellets will be harder to find other than ordering them online which is what most airgun hunters will do even for high quality .177/.22 pellets.  Personally it’s my favorite small game caliber, but you will have to try one for yourself!

.25 caliber/6.35mm

The medium bore .25 caliber hasn’t always been as popular as it is today, with the lack of high quality pellets being the main issue.  The 1/4” slugs are the epitome of a serious hunting round causing massive tissue damage and shock.

The lightest pellets are about 19.91 Grains and easily reach 43 Grain range, though most guns will utilize between 25-30 Grain pellets.  This choice should be a no brainer for most hunters, however that bone crushing energy comes at several costs.

Typically the .25 caliber needs a powerful rifle to drive the heavy pellets effectively at minimum of 40 Ft/Lbs to make it a more viable choice over the .22 caliber, otherwise the pellets are just just traveling too slow.  This is the case with many of the .25 caliber spring/gas piston rifles on the market… The “Quarter Bore” really needs a PCP to realize it’s full potential.

So does this make .25 cal the best caliber for airgun hunting?

Well .25’s are air hogs and you can expect to get fewer shots from a fill of air than the other calibers.  The Benjamin Marauder, for example, gets around 30 good shots in .177 or .22 while only producing 16 strong hunting shots in .25.  This is important to consider if you’re using a labor-intensive hand pump instead of a high pressure tank.  Pellets tend to be a bit more expensive for this caliber as well.

With these things in mind the .25 not only makes a stellar hunting caliber but an awesome long range target shooting due to it’s higher Ballistic Coefficient.  Within reasonable range the .25 can be used to put down medium-sized animals such as coyotes and even smallish hogs with 50-70 Ft/Lbs of energy.

The Best Caliber for Airgun Hunting? It’s Your Choice!

Ultimately caliber selection will depend on the quarry and situation.  For small game you will usually find me carrying a .20 or .22 which will handle 90% of hunting needs.  When I’m going after larger animals or when the shots will be farther, I like a .25 for the added thump.  I rarely use a .177 but have found the caliber to perform very well at closer ranges at lower energy levels to reduce the chance of over penetration.

So there probably is no single best caliber for airgun hunting. They all have a place.  In a future article we’ll discuss the awesome power of “big bores” and big game hunting with air rifles!

Have a great Thanksgiving, and happy hunting!