Height Over Bore
In the world of firearm optics, the height over bore concept plays a crucial role in determining how a shooter engages with their rifle. This principle refers to the vertical distance between the rifle's bore axis and the line of sight through the optic. Some shooters opt to mount their optics higher than the bore line, often achieved through the use of risers or by placing optics on top of carry handles on AR15 upper receivers.
Shooting Stance and Optic Placement
When a shooter mounts their optic higher than the bore line, it forces a change in their shooting stance. Unlike the lower stance favored by those with optics positioned closer to the bore, a higher-mounted optic necessitates a more upright posture. Shooters using this configuration often find themselves standing straighter, with a more natural alignment of their body.
Wider Field of View
One notable advantage of a higher-mounted optic is the expanded field of view it offers. If a shooter's head is rested further to the rear of the buttstock, it expands his perspective. This wider field of view enhances situational awareness, allowing the shooter to better assess their surroundings. This can be particularly beneficial in dynamic shooting scenarios or when engaging multiple targets.
Mobility and Natural Position
The change in shooting stance not only affects the field of view but also contributes to increased mobility. With a more upright position, a shooter can walk with their weapon aimed downrange for longer periods without experiencing fatigue or discomfort. The natural alignment of the body in this stance allows for smoother transitions and quicker responses to changing situations.
Understanding Shot Placement Variance
While the benefits of a higher-mounted optic are evident in stance, field of view, and mobility, shooters must be aware of the potential downsides, particularly in terms of shot placement variance. When an optic is raised above the bore line, the trajectory of the bullet is influenced. If a rifle is zeroed for a specific distance, such as 50 yards, shots at closer ranges (e.g., 20-25 yards) may impact lower than the point of aim, and shots at greater distances may land higher.
This discrepancy in shot placement emphasizes the importance of understanding the rifle's zero and compensating for the variance at different distances. Shooters employing a higher-mounted optic should be diligent in practicing at various ranges to develop a comprehensive understanding of how the optic's height over bore affects shot placement.
The height over bore concept introduces a dynamic element into the world of rifle optics, influencing shooting stance, field of view, and shot placement. Shooters must carefully consider the trade-offs and advantages associated with mounting optics higher than the bore line. While a more upright stance and wider field of view offer clear advantages, the variance in shot placement at different distances requires shooters to be cognizant of their rifle's zero and to adapt their aiming points accordingly. As with any aspect of firearm configuration, finding the optimal height over bore for an individual's shooting style and preferences is a matter of careful consideration and practical experience.