For shooters aiming for long-range accuracy, understanding the nuances of mounting optics is crucial. One key element often overlooked is the Picatinny rail's inclination, measured in Minutes of Angle (MOA). This article delves into what a 20 MOA rail is, why it's used, and its impact on long-range shooting.
Understanding Minutes of Angle (MOA)
Before diving into 20 MOA rails, let's clarify MOA. One MOA is approximately one inch of displacement at 100 yards. While this is an approximation, it's a useful benchmark for understanding adjustments in firearm sights. A 20 MOA rail, therefore, provides a 20-minute angle of elevation (approximately 20 inches at 100 yards) built into the mounting system.
What is a 20 MOA Rail?
A 20 MOA rail is a Picatinny rail that's canted upwards by 20 MOA. This upward cant is integrated into the rail's design, meaning the rail itself is physically angled, not just the scope mounted on it. This pre-inclination significantly impacts how you zero your scope.
Why Use a 20 MOA Rail?
The primary reason for using a 20 MOA rail is to extend the scope's adjustment range for long-range shooting. Here's why:
Increased Adjustment Range:
Scopes have a limited range of vertical adjustment. In long-range shooting, where you need to make significant adjustments for bullet drop at longer distances, this limited range can become a constraint. A 20 MOA rail provides additional vertical adjustment “built-in,” effectively increasing the scope's total usable range. This allows shooters to zero their rifles at longer distances without hitting the limits of their scope's adjustment.
Easier Zeroing at Longer Ranges:
Without a canted rail, zeroing a rifle at extremely long ranges often requires maximizing the scope's upward adjustment, leaving little to no room for making further adjustments during field use. A 20 MOA rail simplifies this process by giving you more room to work with.
Improved Scope Cant:
Proper scope cant is essential for consistent shooting. A 20 MOA rail can assist with maintaining the correct scope angle, especially when dealing with significant bullet drop at long distances.
When is a 20 MOA Rail Necessary?
While beneficial for long-range shooting, a 20 MOA rail isn't always necessary. Consider these factors:
- Shooting Distance: If you primarily shoot at shorter ranges (under 300 yards), a standard, non-canted rail may suffice.
- Scope Adjustment Range: High-end scopes frequently have substantial vertical adjustment ranges. In such cases, a 20 MOA rail might be redundant.
- Caliber & Cartridge: The bullet's trajectory, influenced by caliber and cartridge, plays a role. Cartridges with greater bullet drop at longer distances benefit more from a 20 MOA rail.
Alternatives to 20 MOA Rails
While 20 MOA rails are popular, alternatives exist:
- Higher MOA rails: Rails with greater inclination (e.g., 30 MOA) offer even more vertical adjustment.
- Zero Stop features on scopes: Some scopes include zero-stop features that limit downward adjustment, useful for preventing accidental readjustment.
Conclusion
A 20 MOA rail is a valuable tool for long-range shooters, particularly those using cartridges that experience significant bullet drop at longer distances. By providing extra vertical adjustment, it simplifies zeroing and ensures the scope remains within its optimal adjustment range. However, it's essential to carefully consider your specific needs and shooting style before choosing a 20 MOA rail. Remember to always practice safe firearm handling and consult with experienced shooters or professionals for personalized guidance.
