What do numbers on rifle scopes mean?

What do Numbers on Rifle Scopes Mean?

Rifle Scope Basics

Rifle scopes are an essential piece of equipment for any marksman, whether a novice or an experienced shooter. While they may seem overwhelming to some, understanding what the numbers on a rifle scope mean can greatly enhance your shooting experience. In this article, we will dive into the world of rifle scopes and explore what the numbers on the lens mean.

The First Number: Magnification Power

The first number you usually encounter on a rifle scope is the magnification power, denoted by "X" (e.g., 3-12x). This number refers to the scope’s ability to magnify the image of your target. Think of it as a digital zoom feature on your phone – the higher the power, the closer you are digitally looking.

For beginners, a lower magnification (3-6x) is often recommended. This range provides a clearer view of the target while minimizing the effects of slight wind and movement. Exports and competitive shooters usually prefer higher magnifications (8-12x or higher) for the extra precision and detail at long ranges.

The Second Number: Object Wide Field of View

The second number, often represented as an object wide field of view (e.g., 20-40mm), measures the scope’s angular field of view. This is essentially the scope’s ability to detect movement and track the target. A wider angular field of view translates to a larger portion of the target being observable without having to adjust your aiming point.

For precision hunting and target shooting, a narrower angular field of view (less than 20mm) is preferred, ensuring that the scope focuses precisely on the target. If you’re hunting or scouting in dense terrain, however, a wider angular field of view is beneficial for detecting movements at the periphery of your vision.

Eyepiece Parallax Adjustment

The eyepiece parallax adjustment is sometimes referred to as the ‘first focal plane’ correction. This feature ensures the reticle (lines, dots, or others on the scope’s view) aligns precisely with the target, which is crucial for accurate long-range shooting.

Parallax correction is typically achieved using dial adjustments (rings or buttons) usually located on the top of the scope or an eyepiece sleeve. This adjuster allows you to match the reticle’s plane with the target’s true distance, eliminating any ‘off-center’ issues at different ranges.

Invisible Adjustments: Milliradian (MRAD) and MOA Adjustments

Another crucial aspect of understanding the numbers on a rifle scope is grasping milliradian (MRAD) and minute of angle (MOA) adjustments.

Milliradians (MRAD), typically denoted by °/, are a more scientific method of measuring adjustments in angle. One MRAD corresponds to approximately 0.36 inches at 100 yards. This format allows for precise calculations between various calibers, cartridges, and distances. The MRAD system simplifies calculations, making them easier to understand and more universally applicable.

MOA (Minute of Angle), on the hand, is a more widely understood and used measurement unit, especially among American and Canadian shooters. One MOA is equivalent to approximately 1.5 inches at 100 yards. This system emphasizes more practical, real-life application, making it preferred among hunters and recreational shooters.

Example Adjustments and Calculations

For easier understanding, let’s apply these adjustments to practical calculations. Suppose you’re a rifle hunter aiming at an unsuspecting deer at 100 yards with 1 MOA adjustments on your scope.

Using MOA, you have an adjustment accuracy of 1/minute or 1.5 inches at 100 yards.

If you need to correct your aim by 5 MOA, which represents 7.5 inches at 100 yards (5 x 1.5 inches).

This calculation would require adjustments as follows:

• Rotate turret: 5 times, as each adjustment usually is 1 MOA or 1.5 inches

For MRAD systems:

• Convert 1 MOA to MRAD: 1 MOA = 3.4235 MRAD (account for both the scope’s windage and elevation adjustments) = 17.1652 MRAD
• Since you need to adjust by 5 MOA: 5 x 3.4235 = 17.1655 MRAD
• Determine adjustments: 17.1655 MRAD will equate to approximately 4.5 inches or 4.5-1/4 turn in each direction (remember: MRAD adjustments rely on the scope’s own scales)

Cutting Through the Confusion: Key Takeaways

To distill the essence of these concepts:

• Lower magnification (3-6x) is for beginners, while higher magnifications (8-12x or higher) suit experienced shooters.
• Wider angular fields (20-40mm) are suitable for observing wider areas, while narrower fields (<20mm) are precise for target shooting.
• Parallax adjustment (1st focal plane correction) ensures the reticle aligns with the target for accurate long-range shots.
• Milliradians (MRAD) and MOA adjustments have different units, respectively measured in inches or percentage per 100 yards and angular degrees at various distances.
• In summary, understanding the key points on your rifle scope enables you to communicate effectively with other hunters, adjust your optics accordingly, and gain precise control over your firing capabilities.

By acknowledging these fundamental concepts, whether as a seasoned marksman or a newcomer to rifle shooting, you’ll grow confident in your ability to choose the right scope, communicate effectively with fellow enthusiasts, and make the most out of your shooting adventures.

Summary Table

Here’s a concise reference chart to help you stay grounded:

By grasping these fundamental concepts, the often-intimidating aspects of rifle scopes become transparent and manageable.