How to Sight in a Rifle Scope at 100 Yards

In shooting accuracy is a skill almost all shooters want, but like many aspects of the sport can be very difficult to master. Learning how to sight in a rifle scope for 100 yards is a foundational step to ensure consistent and accurate shots. This guide offers a straightforward approach to aligning your scope effectively. By understanding and correctly setting up your scope, you can improve your shooting accuracy and confidence for various shooting scenarios.

We have recently been covering the topic of shooting at varying distances such as the right scope for 300 yards, so why are we talking about different distances? Well that’s because it matters, 100 yards is one of the more common distances to zero a rifle, weather it’s a hunting rifle, tactical rifle, defense driven rifle etc.

Understanding The Importance Of Sighting At 100 Yards

Long-range shooting brings with it unique challenges. Factors such as wind speed, bullet drop, and the smaller apparent size of distant targets begin to affect the bullet’s trajectory and final impact point. Therefore sighting in or “zeroing” your rifle scope at 100 yards is the first step in being able to make accurate shots at greater distances. When a rifle scope is “zeroed” at a specific distance, it means that the point of aim is aligned with the point of impact at that range. By zeroing in at 100 yards, a shooter establishes a reliable baseline making it easier to adjust for longer distances with increased accuracy.

Shooters who prefer to zero at 100 yards do so because they plan to shoot at this distance, or not significantly farther. What is interesting about 100 yards is this is the highest point the bullet will be, called the maximum orientate, because a bullet will rise after leaving the barrel, reaching its peak point around 100 yards- for most common calibers.

Key Components

To successfully sight in a rifle scope, it’s essential to be familiar with its various components:

1. Reticle: This is the series of fine lines in the eyepiece used for measuring or targeting. Some scopes offer illuminated or varied reticle designs.
2. Elevation and Windage Adjustments: These are knobs usually found on the top and side of the scope. They allow the shooter to adjust the point of impact vertically (elevation) and horizontally (windage).
3. Magnification: This component lets the shooter zoom in and out, making the target appear closer or farther away. This feature is particularly useful for long-range shooting.
4. Parallax Adjustment: Not all scopes have this feature. Parallax is an optical illusion that makes the target appear to move against the reticle when the shooter changes their eye position. The adjustment corrects this illusion.

Before starting the sighting process, please make sure your scope is mounted correctly. If you miss making a mistake here, the rest of the process goes out the window entirely. I’ve been hunting with people whose scope mounts were not tight. As a result of an incorrectly mounted scope, they went home empty-handed and scared off all the animals.

Step 1: Setting Up the Shooting Environment

Choosing the right environment is the first step to accurately sighting in a rifle scope at 100 yards. A designated shooting range with a stable rest and marked distances is ideal.  

At the range, position yourself so you can shoot comfortably and consistently. Sandbags should be placed under the rifle’s fore-end and buttstock to reduce movement, helping ensure that shots are consistent.

Shooting Environment Considerations & Tips

• Platform: An ideal platform is solid, stable, and doesn’t wobble. It should allow for proper alignment of the rifle with the target.
• Safety: Always wear protective eyewear and earmuffs to protect against noise and debris, and ensure the rifle is unloaded until you’re ready to fire. Be aware of your surroundings and always point the muzzle in a safe direction.

Step 2: Preparation

To properly sight in a scope, you’ll need a clear view of your target. While the naked eye might suffice for shorter distances, tools like spotting scopes and binoculars provide a clearer view at 100 yards. This will make the whole process much faster and easier.

Preparation Considerations & Tips

• Rifle Condition: Before sighting in your scope, make sure the rifle is clean, solid, and not wobbly in its stock.
• Comfort With the Rifle: You should be familiar with the rifle’s recoil, trigger pull, and other features. The more comfortable you are with the rifle, the more consistent your shots will be.
• Consistent Shooting Routine: Consistency is key for proficient shooting. This means shooting with the same posture, grip, and breathing pattern every time. Even small changes can throw you off.

Step 3: Bore Sighting and Rough Alignment

Bore sighting is a preliminary method of aligning the rifle barrel and the scope’s reticle. It involves ensuring that the bore (the interior of the barrel) and the scope are aimed at the same target point. The overall goal is to save time and ammunition when fine-tuning the scope’s adjustments on the range. 

This bore-sighting step is unnecessary but can help you zero in quicker. Some people swear by bore sighting, while others do just fine without it. Once you know where you are hitting, you can begin making adjustments.

Bore Sighting Considerations & Tips

• Bore Sighting Techniques: The process can be done using two main methods: visual and laser bore sighting. Visually, one removes the bolt (in bolt-action rifles) and looks down the bore at a distant target, then adjusting the scope to that point. For laser bore sighting, a laser is placed in the chamber, and adjustments are made to the scope until the reticle matches the laser point on the target.
• Tools: Bore sights come as either a caliber-specific laser bore sight or universal laser bore sight that utilizes shims to fit in different rifles.
• Fewer Headaches: Bore sighting saves ammunition, gives a starting point for further adjustments, and reduces frustration when zeroing the scope.
• Additional Adjustments: Bore sighting is just a starting point. Fine adjustments are required afterward when live-firing to ensure precise accuracy.

Step 4: Windage and Elevation Adjustments

When learning how to adjust a rifle scope, windage and elevation are important factors that help the shooter align the point of impact with the point of aim. While windage adjusts the bullet’s impact left or right, elevation adjusts the bullet’s impact up or down.

Windage and Elevation Considerations & Tips

• Adjusting the Turrets: Turrets on a rifle scope allow the shooter to make these adjustments. Most scopes feature tactile clicks, with each click translating to a specific movement at point of impact.
• Click Values: Typically, one click will shift the point of impact by 1/8 MOA (Minute of Angle) to 1 MOA depending on the scope.  At 100 yards 1 MOA is about 1 inch. The click value should be on the scope or adjustment turret, but when in doubt consult the manual. The smaller the adjustment per click the more precise the scope will be as distance increases.
• Calculating Adjustments: Based on the discrepancy between the point of aim and point of impact, calculate the number of clicks needed. For instance, if shots are landing 2 inches to the right at 100 yards and the scope has a 1/4 MOA click value, one would adjust the windage turret 8 clicks to the left.

Step 5: Fine-Tuning and Confirming Accuracy

After making the initial adjustments fire a series of shots in groups of 3-5, to verify the changes and confirm accuracy.

Keep in mind the following:

• Consistent Shooting Routine: Consistency ensures that any changes in the point of impact result from the adjustments, not from different shooting techniques. This means maintaining a steady posture, grip, and breathing pattern.
• Making Final Adjustments: After firing the series of shots, assess the group’s average point of impact and make further adjustments as needed. This may involve a few iterations to ensure the scope is precisely zeroed at 100 yards. Once satisfied, ensure all settings are locked or marked, so they’re not inadvertently altered during future use.
• Are We Finished? Are you happy with the scope being zeroed at 100 yards, or would you like to extend further now that the scope is sighted in? 100 yards is a good distance for an initial zero because most rifle ranges extend this far, but ultimately its up to you.

Final Notes

Sighting in a rifle scope at 100 yards is a process that combines understanding the technical aspects of your scope with the real-world application of shooting. The steps, ranging from setting up a suitable environment and using bore sighting as an initial alignment method to the finer details of windage and elevation adjustments collectively will greatly increase accuracy.

Patience, practice, and attention to detail will make this entire process in learning how to sight in a rifle scope at 100 yards a lot smoother. Even slight inconsistencies or oversights can lead to considerable deviations in long-range shooting. It’s also worth noting that while these guidelines provide a general approach to sighting in, every shooter and every rifle/scope combination is unique. Therefore, continuous practice and adjustments based on your personal experience are important.

Ultimately, whether you’re hunting, tactical shooting, or simply enjoying long-range target practice, having a properly sighted rifle scope is the foundation. So, take the time to understand your equipment, hone your technique, and always prioritize safety. The rewards of precision and confidence in every shot are well worth the effort.

The opinions expressed in this post are those of the author and do not necessarily reflect the views and opinions of Tacticon Armament.