What Is a Bore Sight, Exactly?
Laser Bore Sights and Arbor Bore Sights
The crisp air of the range fills with the scent of gunpowder. You’ve just mounted a brand-new scope on your favorite hunting rifle, eager to experience the superior clarity and precision it promises. The excitement is palpable, but before you can start thinking about that trophy buck or the satisfying “thwack” of a steel target, there’s a crucial first step: sighting in your scope. But how do you start? And how accurate will this initial alignment be? Enter the bore sight, a seemingly magical tool designed to simplify the process and save you precious time and ammunition. But exactly how accurate are bore sights, and are they the complete answer to achieving perfect shot placement? Let’s delve into the world of these handy devices and examine their role in achieving ultimate precision.
At its core, a bore sight is a device designed to visually align the sights of your firearm with the barrel’s bore axis. This alignment helps you get “on paper” at the shooting range, meaning that the first few shots should at least land on the target instead of completely missing it or causing you to search all over the range for a shot.
There are two primary types of bore sights used. The first is a laser bore sight. This device typically fits into the chamber or muzzle of your firearm, depending on the model, and emits a laser beam that travels down the bore. When the firearm is held steady, this beam projects a small dot onto your target, acting as a visual representation of where your bullets should impact.
The other major type is what’s typically known as an arbor bore sight. These tools are typically in the form of a tool that fits into the barrel of a firearm. The arbor bore sight is typically fit to the barrel of the firearm, then you align your scope to the visual center of the tool. This can be a quicker process than some forms of laser bore sights.
How Bore Sights Function (A Quick Look)
The principle behind how bore sights work is relatively straightforward. In essence, they create a visual reference point that mirrors the path your bullet will (ideally) take. A laser bore sight accomplishes this with a laser diode which sends the laser beam down the barrel’s path. An arbor bore sight attempts to use the axis of the barrel to determine alignment. By aligning your scope’s crosshairs (or iron sights) with this reference point, you establish a preliminary correlation between your aiming point and where your bullets are likely to strike.
Where Are Bore Sights Useful?
Bore sights are most commonly employed in several scenarios. First and foremost, they’re incredibly helpful when installing a new scope on your rifle or pistol. Instead of taking a shot, making a large adjustment to your scope, and then repeat, you can start the process without wasting tons of time and money.
Also, they’re beneficial when replacing a scope or other sighting system. Even if you’re swapping a scope for an identical model, small variations in mounting and manufacturing can throw off your zero. A bore sight helps get you back on track quickly.
Bore sights are especially useful when setting up new optics. It can take a number of shots to properly zero a firearm and that can be costly if a scope is not even close to being correct. With the use of a bore sight, you can get right into the meat of zeroing your optic.
Beyond these primary applications, they also offer a convenient solution for initial alignment, especially when you’re short on time or resources. They provide a good starting point before heading to the range to do your final zeroing.
The Benefits: Why Use a Bore Sight?
The advantages of using a bore sight are significant, and they contribute greatly to the overall shooting experience.
Time is money, and bore sights save you a considerable amount of it at the shooting range. Instead of potentially firing dozens of rounds to get your scope roughly aligned, a bore sight allows you to quickly establish a basic zero and minimize your initial sighting-in efforts.
Ammunition is another valuable resource, and bore sights will help conserve it. By getting you on paper with fewer rounds, you reduce your ammunition consumption. This is especially beneficial when sighting in multiple firearms or when working with expensive or hard-to-find ammunition.
Convenience is another major draw. Bore sights are generally easy to use, and the process of using them can be done in a variety of settings. You can use them at home before your trip to the range, allowing you to be more prepared before you start sighting in. You can keep one in your range bag and use it to re-align your scope if it moves or if you want to save some time on zeroing.
Finally, they can actually help prevent damage. You can avoid unnecessary dry-firing and accidental damage to your scope or barrel while getting things aligned.
Accuracy: The Limitations of Bore Sights
While bore sights are undoubtedly useful tools, it’s vital to understand their limitations and accuracy concerns. This is the crux of understanding how accurate bore sights truly are. They are not perfect and are designed to simply provide an estimate.
The primary limitation stems from the manufacturing process itself. While firearm barrels are manufactured with great precision, there are inherent tolerances. Variations can exist in the bore diameter, even within a single barrel. Slight imperfections in the internal dimensions of the barrel, even ones that are seemingly microscopic, can impact the trajectory of the bullet.
Concentricity is another key factor. The bore of the barrel and the chamber where the round sits must be perfectly aligned. Any deviation, no matter how small, can influence bullet trajectory.
Also, there are imperfections of the barrel itself. Even a high-quality barrel may have slight imperfections that affect the bullet’s flight path.
User error is another significant factor. Even with the best bore sight, achieving perfect alignment depends on your technique. Improper centering of the laser unit or bore sight tool within the bore can introduce inaccuracies. Likewise, not having the firearm held perfectly level or securely during the process can lead to problems. Similarly, any misalignment of the scope or sights relative to the bore sight’s reference point can undermine the accuracy.
Distance also plays a role. The further your target is from the muzzle, the more any alignment error is amplified. A small deviation at a close distance can translate to a significantly larger miss at 100 yards or beyond.
How to Use a Bore Sight Effectively
To maximize the effectiveness of a bore sight, follow these steps:
First, select the correct bore sight for your firearm. Choose one that is compatible with your specific caliber and barrel type.
Next, carefully follow the manufacturer’s instructions. This includes securely inserting the laser unit into the barrel or attaching the arbor bore sight.
If using a laser bore sight, ensure the firearm is stable. Use a bench rest or shooting stand to keep it as level as possible.
Adjust your scope’s elevation and windage adjustments to align with the laser dot. This gets your scope’s crosshairs on or near the laser dot.
After using a bore sight, you will still need to finalize it with live-fire. Remember that a bore sight should not be the end of the process, but rather the beginning.
The Importance of Live-Fire Zeroing
The term “zeroing” refers to the process of adjusting your firearm’s sights or scope so that your bullets consistently strike the desired point of impact at a specific range. This is achieved by carefully adjusting your scope’s windage (left/right) and elevation (up/down) adjustments based on where your shots are landing on the target.
Live-fire zeroing is essential for achieving the highest level of accuracy. It takes into account many factors that a bore sight simply cannot replicate. Every firearm and every load of ammunition is unique. The bore sight can only get you close to where your shots will land. Live-fire allows you to fine-tune the adjustments to achieve the precise accuracy you want.
How to Zero a Rifle at the Range
The best way to zero a rifle is through live-fire and can be done at most shooting ranges.
Start by ensuring your firearm is safely unloaded. Place your target at the recommended distance, such as 100 yards for a rifle.
Start with a bore sight to help you get on paper. Then, carefully fire a group of three to five shots. Analyze your group. If your shots are not on the bullseye, adjust your scope’s windage and elevation settings, then fire another group. Repeat this process, making small, incremental adjustments until your shots consistently strike the bullseye.
Accuracy in Comparison
So, how accurate are bore sights versus live-fire zeroing? Bore sights will almost always get you “on paper” at a specific distance, but they rarely provide the ultimate level of accuracy. This is because of all of the limitations listed earlier.
With a bore sight, you might expect your shots to be within several inches of your point of aim at 100 yards. If you’ve done a great job with the bore sight, you might even be closer. But after live-fire zeroing, you should be able to achieve group sizes that are much tighter.
Conclusion
In conclusion, bore sights are incredibly valuable tools for any shooter, offering a fast and convenient way to get your scope or sights roughly aligned. They save time and ammunition and can be especially helpful when mounting or swapping optics. However, it is important to remember the limitations of bore sights.
The crucial takeaway is that while bore sights are a great starting point, they are not a replacement for live-fire zeroing. Live-fire zeroing is essential for achieving the highest level of accuracy and ensuring your shots hit their intended mark at the desired range.
So, the next time you mount a new scope, use a bore sight as a helpful starting point, but be sure to confirm your zero with live-fire. Head to the range, embrace the process, and experience the satisfaction of hitting your target with confidence.
