What Is Rifle Cant?

Rifle cant refers to the rotation or tilting of the rifle. This tilt is often unintentional and typically results from inconsistent shooting technique, uneven terrain or improper equipment that prevents the shooter from levelling the rifle properly. Even a small degree of cant can cause a noticeable shift in the bullet’s point of impact.

When a rifle is canted, the optics line of sight or the calculated aiming point, no longer intersects the bullet's trajectory at the expected point. This angular misalignment causes the bullet to follow a trajectory that deviates from the expected path. As the range increases, the linear displacement caused by cant becomes more pronounced due to the longer travel time and greater arc of the bullet.

Defining Scope Height (Sight Height)

Scope height, also known as bore height, is the vertical distance between the centerline of the rifle's bore and the center of the optical sight. This parameter is essential in ballistic calculations because it affects the initial alignment required to zero the rifle.

Before zeroing, the bullet’s natural trajectory lies beneath the line of sight. Therefore, to make the bullet’s path intersect with the shooter’s aim at a specific distance, the scope’s line of sight is adjusted so that it intersects the bullet’s trajectory at the desired point, known as the zero.

When a scope is mounted higher, the angle between the bore and the line of sight must be increased during zeroing. This steeper angle is necessary to ensure that the projectile intersects the line of sight at the desired range. However, once zeroed, the bullet’s path and the line of sight intersect just the same, regardless of scope height.

Dispelling a Common Misconception

A common misconception among shooters is that cant errors are more severe when the scope is mounted higher above the bore. This stems from the assumption that the increased angular divergence during zeroing makes cant-related deviations worse.

While it is true that a higher scope requires a steeper initial alignment, this does not influence how cant affects the bullet after zeroing. Once a rifle is zeroed at a specific range, the system is effectively calibrated to that distance. Whether using elevation turrets to dial in a new range or employing holdovers on a reticle, the shooter is re-establishing a zero at that point. The bullet’s trajectory and the line of sight intersect as planned.

If the rifle is then canted, the bullet’s POI will shift based on the angular displacement and the target distance, not the scope height. In both dialing and holdover scenarios, the system’s angular geometry is what determines the nature of the cant error. The height of the scope does not change the degree of angular rotation because cant is a rotational deviation.

A 10-degree cant is the same geometrical condition whether the optic is mounted 1.5 inches or 2.5 inches above the bore.

This principle is supported by empirical evidence. For instance, a study by MDT demonstrated that the impact of cant remains unaffected by scope height. They concluded that "if you use a dialed solution, or a reticle-hold, it is the same; in both cases the scope height does not affect the amount of error from cant".

Conclusion: Precision Hinges on Proper Understanding

Rifle cant and scope height are often misunderstood in their interaction, but clarity on this topic is essential for precision shooters. The evidence is clear: cant errors are purely a function of angular displacement, the rotational misalignment of the rifle, and not influenced by the vertical distance between the optic and the bore.

Whether your scope is mounted high or low, a given degree of cant produces the same deviation in point of impact.

This understanding frees shooters from a common misconception and allows them to focus on what truly matters: maintaining a level rifle and consistent technique. Tools like bubble levels, combined with deliberate practice and awareness, play a far greater role in mitigating cant errors than scope height ever could.

That said, scope height remains relevant in other areas. A higher-mounted optic can improve ergonomics, reduce strain in awkward shooting positions, and even provide a visual cue that makes cant more noticeable to the shooter, all contributing indirectly to better performance in the field.

By separating fact from fiction, shooters can make more informed decisions about their gear and technique. Mastery begins with understanding, and in precision shooting, that understanding must be grounded in geometry, not assumptions.