Air Rifle Scopes, Simply Explained

Air rifle scopes are an often confusing subject for new and more seasoned hobbyists alike.

However, there are some basic considerations and terminology that, once understood, can make the process of choosing a scope much easier and even enjoyable.  And a good scope can really take your accuracy to the next level.

After you’ve given this article a read, please check out our comparison table of some of the top-rated and best-selling air rifle scopes on amazon.com.

Why is an Air Rifle Scope Necessary?

Many people assume that a conventional rifle scope can be used in place of an air rifle scope.  However, this can be a costly mistake.  In particular, gas/spring-piston, and many higher-powered air rifles create lots of recoil, but not just the typical, unidirectional recoil of a conventional firearm.  Rather, there is two-way recoil:  at first when the large spring mass uncoils (or gas-piston is released), which sends the rifle backwards, and again when the piston reaches the end of its length, which jars the rifle forwards.  This “double recoil” wreaks havoc with lenses and delicate internal parts and can destroy an ordinary scope within a few shots.

Fixed vs. Variable Air Rifle Scopes & Ocular Magnification

The first consideration is whether you want a fixed or variable scope.  In this case, we are talking about the eyepiece (ocular) magnification (the lens you look through).  For example, for fixed scopes, such as a 4x32 or a 6x32 models, the first number – the “4” and “6” in these scenarios – refers to the number times the target is magnified.

Higher magnification is great when sighting in more distant targets; however, take note that the higher the magnification, the smaller your field of view becomes.  Just like a camera or microscope, the bigger you enlarge the image, the less of the surrounding area can enter the picture.  In addition, as magnification increases, less light penetrates the scope and the image will appear darker.  So, in the case above, a target viewed by the  6×32 scope would be darker than a 4x scope, as well as having a smaller field of view.

Fixed air rifle scopes, with their typically lower magnification and large field of view, are good for shooting at closer ranges and sighting moving targets quickly, therefore making them ideal for dispatching pests and small game hunting.  In addition, because they don’t have much in the way of moving parts, they can often be simpler to use and bit more durable.

Variable air rifle scopes, on the other hand, have a range of ocular magnification.  For example, in these scopes, the eyepiece can might be adjustable between 3 to 9 times or 4 to 12 times magnification –  3-9x32 or 4-12x32, for example. respectively.  As such, variable air rifles can provide the best of both worlds – low magnification and a large, bright field of view for close range shooting, and greater magnification when needed for approaching more distant targets.  Although there are many to choose from, variable scopes that range from 3-9x or 4-12x are a good bet for most users and applications.

Air Rifle Objective Size

So this refers to the second number, after the “x” – i.e., 4-12x50, for example.  In this case, the “50” refers to the size of the objective lens, which is the lens that faces away from you.

The important thing to remember about the objective is that, the larger it is, the more light can enter the scope and therefore enhance image brightness when fixing on distant targets at higher ocular magnification.  Nevertheless, simply getting a scope with a big objective doesn’t avoid the problem of high magnification darkening, but it can help in dim conditions.

Objectives ranging from 32 mm to 50 mm are fairly common and should be sufficient for most users.  Remember that the bigger the objective, the more clearance from the rifle is needed, and the heavier and bulkier the scope becomes overall.  As a result, think twice before going for a monster scope because it looks cool, you will most likely regret the decision and it will almost certainly not improve your accuracy.

Understanding Parallax Adjustment

The Parallax effect is probably the most confusing of all concepts concerning rifle scopes.  Stated simply, the word parallax refers to the phenomenon by which a fixed object’s location may appear to move due to changes in the viewer’s line of sight.  There are many equally confusing so-called “examples” of this effect, but let me give you the easiest one I can imagine.

This diagram shows how a fixed object can appear to move when viewed from two different lines of sight.
“Parallax Example” By Booyabazooka under CC-BY-SA-3.0

Make a thumbs-up sign and extend that arm in front of your face.  Keep your eyes on your thumb and keep your arm still.  Now, close one eye and keep the other trained on your thumb.  Now do the same with the other eye, holding your in the same position the whole time.  Do you see that each time you switch eyes the image “appears” to move right and left.  Now do the same but put your thumb a few inches from your face and repeat – do you see how the apparent movement is further exaggerated?  This is the same thing that happens when you look through your scope and you move your head slightly to the left or right; each time you move you change your line of sight just enough to make the target appear to move, and this effect is more pronounced at close ranges.

What Does “AO” Refer to?

The way modern air rifle scopes often deal with parallax is with an adjustable objective – typically, this is the significance behind the “AO” designation on most models.  These scopes usually come with an adjustable ring around the objective, although some others have the adjustment located in the sighting turret.  The “aim” of adjustable objectives is to minimize the parallax effect and keep the reticle (crosshairs) on your target regardless of distance and subtle changes in viewing angle.

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Choosing a Reticle Type

The word “Reticle” is just a fancy word for the crosshairsa scope is equipped with.  There are many kinds of reticles, most of which are old, outdated or simply not useful for air rifles, where accuracy and relatively small kill-zones are the rule.  As a result, we won’t be discussing reticles used by German U boats or those fitted in WWII M4 Sherman tanks!

Here are the most common and useful reticle configurations for most modern air rifles scopes.

Fine Crosshair

This is the simplest configuration, with two very thin lines crossing in the center of the field of view.  Given its thin line weights, this is still a favorite among many airgunners since it covers very little of the target.  However, the problem is that these thin lines are also very easy to lose against dark backgrounds, which is often the case when hunting in and around vegetation or more dimly-lit areas.  Consequently, the fine crosshair is best suited for shooting against fixed, high-contrast backgrounds/targets where rapid sighting and the fine lines are not a problem.

Duplex Crosshair

The duplex crosshair is a big improvement over the fine crosshair for air rifle enthusiasts as it comes with thicker hairs along the periphery of the field of view.  A common version of the duplex is the “R4” Reticle.  The thicker lines and thin center hairs help mitigate the problem of losing the hairs against vegetation/darker backgrounds while still minimizing any coverage of the target around the bulls-eye.  This makes the duplex crosshair the reticle of choice for many airgunners.

Mil-Dot

A variation on the duplex crosshair, the mil-dot has small dots along the fine lines toward the center of the hairs.  The dots provide various targeting zones and can potentially be used for range finding, although most air rifle enthusiasts won’t need (or bother) with this capability.

Like the duplex style, this reticle permits good sighting against darker backgrounds while minimizing coverage (obscuration) smaller targets.  The mil-dot is probably the most popular of all reticle types, with many variations on the theme, such as the “P4” sniper reticle.

Target Dot

This is basically the fine crosshair configuration with a center dot.  This reticle type has the same drawbacks as the fine hair type, in addition to the threat of covering up small targets.

Consequently, it is not a very useful sight for hunting or distance shooting in our view.

Circle

Much like the target dot, but with larger, thin-lined circle around the bulls-eye instead. We have the same problems with losing the hairs and covering/cluttering the target as with the target dot.

Air Rifle Mounts

The vast majority of air rifles are fitted with “dovetail” mounts, although many use “weaver” mounts. Make sure you know which type your air rifle requires before purchasing a scope!

Scope Pins/Stops

To prevent your scope from “creeping” along the mounting rail, particularly due to the heavy double recoil of spring-piston guns, many scopes/rifles come with stops pins or plates that secure the scope and prevent it from moving.  The scope is simply backed up flush to the appropriate pin/plate placement and secured there. It’s important to ensure there is no play between the pin and the scope.

One Piece vs. Two Piece Mounts

A one piece mount is thought to offer more stability as it grips the rifle and scope across a greater area and also better resists side to side torquing.  We agree, although one-piece mounts can be a bit more pricey than two piece counterparts.  A one piece mount is probably most suited for very powerful spring rifles, given the much greater dual recoil these guns produce.  If you are using a precompressed or multi-pump pneumatic air rifle, a one piece mount is almost always unnecessary.

Barrel Droop & Barrel Misalignment

This is not so much about air rifle scopes, but does affects their accuracy.  Very often air rifles will leave the factory with barrels that aren’t perfectly straight. They may depart from “true” either upwards or downwards or side to side; however, a “drooping” or downward-pointing barrel is the most common.  Often cited as an issue with more inexpensive rifles, this could affect virtually any rifle, and make sighting-in with even the best scope problematic.

In addition, while scopes come with horizontal/vertical adjustment, there is only so much adjustment that can be done.  The erector tube, which contains the reticle and what moves with such adjustments, is normally held in place with a spring.  As a result, if you try to correct a drooping gun by nearly fully unscrewing the elevation adjustment to bring up your shots, there may be little or no spring tension left to keep the erector tube in place.  In such case, when you next fire the rifle, even the slightest recoil can bounce the reticle around in random fashion, making your sighting problem much worse!

If you find yourself pushing the limits of your scope’s elevation adjustment to compensate for a drooping barrel, consider instead adding a very thin shim to the mount instead.  This can take the form of a piece of soda can or any other thin, inert material that you cut to fit into the site mount and prove just a little boost to scope.  Place it in the rear of the scope in a one-piece mount, or the mount closest to the shooter in a two-piece mount.  And if this still doesn’t give you enough height, consider an adjustable scope mount, which will give you much more flexibility to line up a drooping rifle.

Break Barrels & Barrel Misalignment

According to some reputable sources, break barrel rifles are inherently vulnerable to barrel misalignment due to their very nature – i.e., the routine breaking of the barrel when cocking the rifle.  It is believed that this constant movement promotes slight but significant changes in barrel orientation relative to the scope, which in turn makes them hard to sight in or accurately.

While we think this is less of a concern with higher-quality springers, it is definitely an issue and can potentially affect any break-barrel rifle after enough use.  Of course, if you are using open sites, this is no issue at all, since open sites are are not affected by drooping.

Nevertheless, if you want pinpoint accuracy and are anxious to use a high quality scope, we suggest you stick with fixed barrel models (like pneumatic/PCP rifles) or underlevers or sidelever spring guns, which don’t require breaking of the barrel.

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