Boresighting is a quick and inexpensive method for roughly aligning a rifle's scope with its barrel. It's often used as a preliminary step before heading to the range for zeroing. But how accurate is a bore-sighted rifle, really? The answer, unfortunately, isn't a simple yes or no. It depends on several factors. This article delves into the limitations of boresighting and explores what you can realistically expect from this technique.
What is Boresighting?
Boresighting involves using a boresighting tool, a device that fits into the barrel of your rifle and allows you to align the scope's crosshairs with the bore (the inside of the barrel). The tool simulates the path of the bullet, allowing you to get a rough alignment without firing a single shot. This is particularly useful for new scopes or after major work on the rifle.
Advantages of Boresighting
- Speed and convenience: Boresighting is much faster than traditional sighting-in at the range.
- Cost-effectiveness: No ammunition is required.
- Safety: Eliminates the risk of accidental discharge during the initial alignment process.
- Preliminary alignment: Provides a starting point for more precise zeroing at the range.
How Accurate Is Boresighting? The Reality Check
While boresighting gets you in the ballpark, it's not a precise zeroing method. Expect significant deviations, particularly at longer ranges. Several factors contribute to this inaccuracy:
- Tool Imperfections: Even high-quality boresighting tools have inherent inaccuracies. Manufacturing tolerances and slight variations can affect the alignment.
- Barrel Variations: The bore itself isn't perfectly straight. Minor imperfections and variations in rifling can cause slight bullet deviations.
- Scope Mounting: Improper scope mounting is a frequent source of error. Even a small misalignment of the scope rings can lead to significant point of impact shifts.
- Ammunition Variations: Bullet variations in weight and consistency can also affect accuracy.
Common Expectations: While some sources claim boresighting can get you within a few inches at 100 yards, this is optimistic in most cases. A more realistic expectation is to be within several feet, potentially more at longer distances. Consider it a starting point, not a final result.
Factors Affecting Boresighting Accuracy
Let's delve deeper into some key factors that influence how effectively boresighting aligns your rifle:
1. Type of Boresighting Tool
The quality and precision of the boresighting tool directly impact the accuracy of the initial alignment. Laser boresighters are generally more accurate than those using a visible alignment rod, though even laser boresighters will have some margin of error.
2. Rifle Condition
A rifle with a damaged or worn barrel will likely yield less accurate results from boresighting than a well-maintained rifle.
3. Scope Quality and Mounting
High-quality scopes, properly mounted, are critical for maximizing the benefits of boresighting. A poorly mounted scope will negate the accuracy of even the best boresighting tool. Ensure your scope is securely mounted and aligned correctly within the rings.
4. Environmental Factors
Extreme temperature changes can affect the accuracy of the boresight, potentially leading to greater inaccuracies at the range.
Case Study: Comparing Boresighting to Range Zeroing
A recent informal experiment comparing boresighting to range zeroing involved 10 participants and 5 different rifles. While boresighting got them on paper at 25 yards, adjustments of 1-3 inches were needed at 100 yards. At 200 yards, adjustments exceeding 6 inches were common. This highlights the limitations of relying solely on boresighting for accuracy.
Conclusion: Boresighting as a First Step
Boresighting should be viewed as a convenient initial alignment method, not a replacement for proper zeroing at the range. While it can save time and ammunition by getting you into the general vicinity of your target, expect to make significant adjustments once you're on the range. Always prioritize proper range zeroing for optimal accuracy and safety. Think of boresighting as a starting point for fine-tuning your rifle's accuracy, not the end goal.