How Far Back to Mount Scope on AR: A Comprehensive Guide
When it comes to mounting a scope on an AR rifle, one of the most crucial decisions you’ll make is determining how far back to position the scope. This decision can significantly impact your shooting accuracy, comfort, and overall experience. In this detailed guide, we’ll explore various factors to consider when deciding how far back to mount your scope on an AR rifle.
Understanding Scope Mounting
Before diving into the specifics of how far back to mount your scope, it’s essential to understand the basics of scope mounting. An AR rifle typically uses a Picatinny or Weaver rail system for mounting scopes. This rail system allows for various scope mounts and rings to be attached to the rifle’s upper receiver.
Scope mounts come in different heights, which determine how far back the scope is mounted from the rifle’s bore. The distance between the bore and the scope’s optical center is known as the eye relief. Proper eye relief is crucial for comfort and safety, as it ensures that your eye is at an appropriate distance from the scope’s lens to avoid eye strain and potential injury.
Factors to Consider
Several factors should be considered when determining how far back to mount your scope on an AR rifle:
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Scope Height: The height of your scope’s mount and rings plays a significant role in determining the overall height of the scope. Higher mounts and rings will result in a higher scope, which may require a longer eye relief and a taller cheek riser or stock to maintain a comfortable shooting position.
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Optical Center: The optical center of the scope is the point where the scope’s optical system is aligned. This point should be as close to the rifle’s bore as possible to minimize parallax errors and ensure accurate shooting.
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Eye Relief: As mentioned earlier, proper eye relief is crucial for comfort and safety. The recommended eye relief for most AR rifles is between 3.5 to 4 inches. However, this can vary depending on the specific scope and rifle combination.
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Shooting Style: Your preferred shooting style can also influence the scope mounting distance. For example, if you plan to shoot from a prone position, you may need a longer eye relief and a lower-mounted scope to maintain a comfortable shooting position.
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Barrel Length: The length of your rifle’s barrel can also affect the optimal scope mounting distance. Longer barrels may require a lower-mounted scope to maintain a comfortable shooting position, while shorter barrels may allow for a higher-mounted scope.
Calculating Scope Mounting Distance
Calculating the optimal scope mounting distance involves a few simple steps:
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Measure the height of your scope’s mount and rings. This information can typically be found in the scope’s manual or on the manufacturer’s website.
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Subtract the height of the mount and rings from the total height of the scope. This will give you the distance between the scope’s optical center and the rifle’s bore.
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Ensure that the resulting distance falls within the recommended eye relief range for your specific scope and rifle combination.
For example, if your scope’s mount and rings are 1.5 inches tall and your scope is 6 inches tall, the distance between the scope’s optical center and the rifle’s bore would be 4.5 inches. If your scope and rifle combination requires an eye relief of 3.5 to 4 inches, this mounting distance would be suitable.
Table: Recommended Scope Mounting Heights
| Scope Height | Recommended Mount Height | Recommended Eye Relief |
|---|---|---|
| 4 inches | 1.25 inches | 3.5 to 4 inches |
| 5 inches | 1.5 inches | 3.5 to 4 inches |
| 6 inches | 1.75 inches | 3.5 to 4 inches |
| 7 inches |
