Optics - Rifle Scopes

Low-Power Variable Optics (or LPVOs) are compact riflescopes that offer a 1x or 1.5x minimum magnification, suitable for close-quarters engagements. For further engagements, these scopes can be turned up to their maximum magnification, which may range from 4x to 10x. Offering maximum flexibility, LPVOs promise a both-eyes-open “red dot” type of sight picture that is agile at close range, plus the ability to increase magnification for confident target identification and accurate shooting out to greater distances.

If you’re looking for the most versatile carbine scope possible, Low-Power Variable Optics are tough to beat. Without a doubt, LPVOs are the most flexible scopes when engaging targets at both close range and distance. At 1x they are faster to use than 2.5x-5x fixed magnification prism scopes, yet they also offer additional magnification for easier use at further distance.

Of course, there is a trade-off with LPVOs as well. Compared to a red dot or prism scope, LVPOs are larger and heavier than any other carbine or short-range optic. You will also have to purchase an additional mount to match the optic diameter, which can make LPVOs more costly than other optic options.

Medium-Power Variable Optics include rifle scopes with a minimum magnification of 2-4x and a maximum magnification of 9-15x. Traditionally, the most popular medium power magnification range was 3-9x, although new optical technologies have made 2.5-10x increasingly commonplace. These rifle scopes trade some agility for added magnification and clarity at longer distances.

Medium-Power Scopes offer greater effective range, making them a suitable choice for hunters and marksmen who prefer to ‘zoom in’ and take precise shots from 50 yards and beyond. After all, if you’re not taking a rifle into close-quarters, there is little reason to compromise your precision for a lower minimum magnification.

Naturally, a larger scope will add even more bulk and weight than LPVOs. It will take much more practice to shoot comfortably with both eyes open, and the sight picture will not be as fast at low magnification, but if you’re after strong general precision, these scopes are a great option.

High-Power Variable Optics, usually referred to as ‘Precision Rifle Scopes’, usually feature maximum magnification ranging from 15x to 30x and beyond. These scopes can be big, heavy, and somewhat expensive, but if you’re looking to land shots at extreme distances, a good Precision Rifle Scope will be necessary to achieve your goals.

These rifle scopes will make your rifle entirely impractical to shoot standing up at the close range, as they are designed for supported shooting from a bench or the prone position. That said, if you really want consistent accuracy at serious distances, there is no substitute for a high magnification precision scope. When you’re sizing up a target at a kilometer or more, your optic is almost as important as the rifle itself. You’ll need exceptional glass clarity to ID your target while estimating wind speeds and target distance.

The size and weight of these rifle scopes combined with the need for repeatable precision demands a stout, heavy and expensive mounting system. Also, pricing for these scopes starts higher than the other rifle scope options and climbs even higher. If you’re getting into precision rifle shooting, don’t expect to save any dollars. You might use less ammo, but you’ll find yourself in a highly addictive sport that demands constant investment.

Reticle refers to the sight picture or aiming point(s) you see when looking through the scope. The oldest reticles were simple crosshairs made of wire or even silk thread physically strung across the scope tube. Almost all modern rifle scopes now use chemical or laser etching, which can reproduce complex shapes with tremendous consistency. A huge variety of reticle types are now available. The reticle you choose should depend on your performance expectations and what kind of shooting you intend to do with your rifle. Traditional duplex crosshairs are thin in the center and thicker towards the edges.

Mil-dot reticles utilize methods of target range estimation and bullet drop compensation adopted by the US military about 40 years ago. Long range precision scopes often feature MIL-grid reticles, an expansion of the mil-dot concept with standardized holdover points to help the shooter account for wind as well as bullet drop at any target distance.

Bullet drop compensation reticles are pre-calibrated to match certain calibers fired at certain velocities, giving simplified aiming cues that approximate the bullet’s impact at increasing distances.

Primary Arms champions the Advanced Combined Sighting System (ACSS®), a state-of-the-art reticle concept combining range estimation, moving target leads, bullet drop compensation, and wind holds into the scope’s sight picture.

Some scopes offer reticle illumination through a battery-powered LED emitter or fiber-optic tube, which shines a light on the etched reticle’s reflective coating. The light scatters back towards the shooter’s eye, changing the color and brightness of the reticle.

Reticle illumination helps create a stronger contrast between the reticle and the target for improved speed and accuracy, especially in low light conditions like dawn or dusk. Red and green are the most popular reticle illumination colors. In partially illuminated reticles, only a specific section of reticle has been treated to reflect light, usually to give the user a simplified, faster sight picture when shooting in challenging lighting conditions.

These refer to mathematical angular units of measure.

The Minute of Angle (MOA) system is the traditional choice for US Marksmen, with 1 MOA covering a circle measuring 1.047 inches at 100 yards. This is easier for many Americans to understand, as the ballistic equations translate inches to yards.

If you prefer to stay within units (or use metric), the Milliradian (MRAD or MIL) system is your choice. Mathematically, 1 Milliradian always equals 1/1000 the distance to your target. In layman’s terms, this means 1 meter at 1000 meters, 1 yard at 1000 yards, or 3.6 inches at 100 yards. MILs have grown in popularity due to their usage in the military. Since MILs are a proportional constant that works across Standard and Imperial units, it’s easy to translate when working with global marksmen.

Regardless of which system you choose, your scope’s turret adjustments should match the reticle’s units. Scopes with MOA reticles should feature 0.5 or 0.25 MOA-per-click adjustments, while scopes with MIL reticles should feature 0.1 MIL-per-click adjustments. There is one exception, though. For low magnification scopes featuring BDC reticles and other ‘set and forget’ designs, your adjustment units are not very important, since you’ll never be using the turrets outside your initial zero. You can get a much better understanding of MOA and MRAD in our in-depth article, MIL vs MOA vs BDC.

Second Focal Plane (SFP) optics feature a reticle that stays the same size relative to the field of view at all magnification settings. Whether at minimum or maximum magnification, the sight picture will always stay constant. Popular hunting scopes are usually second focal plane because the reticle will not obscure your target at maximum magnification. Generally, you will leave your hunting scope at minimum magnification while scanning for game, and then you can adjust to maximum magnification for your shot.

The advantage of SFP scopes is that they are usually less expensive than similar first focal plane optics. The disadvantage of SFP scopes is that advanced reticle features like bullet drop compensation can only be “true” and correct at one magnification setting, usually maximum magnification.

First Focal Plane (FFP) optics feature a reticle that stays the same relative to the target, not to the field of view. As you ‘zoom’ from minimum to maximum magnification, the reticle will appear to grow as the target becomes larger inside the field of view. The advantage of FFP scopes is that the reticle’s advanced features are always accurate, regardless of the magnification setting. The only disadvantage of FFP scopes is that they usually cost more than their SFP equivalents.

Low magnification scopes are more likely to use the SFP configuration, while high magnification hunting or precision optics are more likely to use the FFP configuration. You can dive deeper into understanding FFP and SFP by checking out this Scope University article.

These control the position of the reticle relative to the target being viewed through the scope. Initially, you use the turrets to zero the optic so that point of aim coincides with the bullet’s point of impact at a specified distance.

For precision shooting, the marksman may compensate for ballistic drop with elevation adjustment. Windage adjustment is rarely necessary, as most professionals will simply hold for crosswinds.

Some scope turrets integrate features like a zero reset, adjustment lock, or zero stops. Zero-resettable turrets can be configured to read “0” after initial zeroing, making subsequent adjustments for range and wind much easier to work with, and providing an easy reference to check that the turrets have not been accidentally turned or bumped out of their intended position.

Locking turrets can be locked into a position the user determines, helping prevent accidental scope adjustment during rough handling. For many scopes, this lock is only set for their zero position.

Finally, some scopes intended for long-distance precision shooting feature a ‘zero stop’ elevation turret. Zero stop turrets allow the user to mechanically set a point where the turret’s rotation will physically stop. In case the optic needs to be returned to its original zero quickly after being adjusted for a long-range shot, the turret can be spun back down to the rifle’s original “zero” without the need to carefully count clicks or observe the turret’s markings.

A scope’s diopter helps keep your reticle in focus, and every marksman’s optimal setting will be slightly different depending on their eyesight.

You only need to set the diopter once to use the reticle at any distance. Follow the instructions in your scope manual to ensure that your diopter is set properly before you go to the range.

Parallax error occurs when the target’s image and the reticle are not aligned on the same focal plane inside the scope. Eliminating parallax error brings the reticle into the same focal plane as the target, maximizing accuracy and consistency.

While eliminating parallax error also brings the target into sharp focus, parallax and focus are not the same things. Parallax error is most noticeable at high magnifications and most important in precision shooting.

Lower magnification scopes like prisms and LPVOs are generally set to eliminate parallax error at 100 yards only, with no adjustment feature.

Tube size refers to the diameter of the main body of the scope tube. The most common tube sizes are 1-inch and 30mm, but 34mm and 35mm scope tubes are popular in premium long-range optics, as the wider diameter allows for more internal elevation adjustment.

When choosing a mount or rings for your scope, it is crucial to match dimensions with the scope tube size.

This refers to the distance between the edges of the scope’s sight picture at a certain magnification. The field of view is usually expressed in feet, at 100 yards, at a specific magnification.

For example, the Primary Arms 1-6x Gen III scopes have field of view listed as “110 feet @100 yards at 1x” and “19.3 feet @100 yards at 6x”. Imagine standing at one end of a football field and having a friend stretch a tape measure across the end zone 100 yards away.

Looking through the scope at 1x, you would be able to see 110ft of tape measure from one edge of your sight picture to the other. Cranking up magnification to 6x, you would be able to see 19.3ft of tape measure from edge to edge.

Although field of view generally varies with magnification, not all rifle scopes feature the same field of view at the same magnification. All else being equal, maximizing field of view is desirable.

Eye relief is the ideal distance between the ocular lens at the rear of the scope and the shooter’s eye. Eye relief can be expressed as a range, for example 3.3-3.5 inches.

This either indicates that the ideal sight picture can be obtained anywhere between the two measurements, or that the ideal measurement changes slightly as magnification increases. Rifle scopes with a shorter eye relief tend to feature more field of view.

Scopes with a longer eye relief can be mounted on high recoiling firearms without risk to the shooter’s eye as the optic violently moves rearward with each shot.

Exit Pupil is the diameter of the shaft of light coming out of the ocular lens located at the back of the scope. To look through the scope, the pupil in your eye needs to look down that shaft of light. Exit pupil is a function of objective lens diameter divided by magnification, so the same scope can have a generous exit pupil at low magnification and a much smaller exit pupil at high magnification.

The human eye can only open to a maximum diameter of around 7mm, so old arguments held that exit pupil specifications larger than 7mm were wasteful, since the scope is delivering more light than your eye can accept anyway.

In recent years, however, the close relationship of exit pupil to ‘eye box’ has become understood. Eye box describes the usable space behind an ocular lens where you will have clear view of the scope image.

A wide exit pupil creates a large, forgiving eye box, making it easier to find the reticle through the optic and take an accurate shot even if the eye is not perfectly aligned with the scope’s centerline.