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What is a Rifle Scope Inclinometer?

Shooters generally have to deal with challenging environments and uneven ground. From hilly slopes to rocky forests, it often becomes tricky to accurately hit your target when you have to include an angle in your calculations.

What is a Rifle Scope Inclinometer

In previous times, this slope was calculated with the help of a protractor, a piece of string, and something to help hold the string, such as a paper clip. Not only was this method not a hundred percent accurate, but it was also very time-consuming, a major problem when shooting moving targets especially at long-range.

Now, there are devices that shooters can make use of to improve their aim when shooting at an angle. These devices help you to account for gravity, bullet drag and increased time for shooting at an angle.

Using the Right Device

There are tools that can help shooters shoot at a decline or an incline. These include an inclinometer or an angle cosine indicator.

What is an Inclinometer?

An inclinometer (or clinometer) is a tool used to measure the tilt of a slope (the angle), and the projected elevation/ depression of an object impacted by gravity. They are particularly useful when shooting at steeper angles.

The inclinometer may be mounted on top or to the side of your scope. It is preferable to mount it on the side so that it doesn’t have to be moved around when taking the shot and using it in your angle estimations.

What is an Angle Cosine Indicator (ACI)?

An angle cosine indicator measures the projected distance a bullet will travel by taking into account the straight line distance as well as the horizontal path. By measuring this distance, shooters can avoid aiming too high by only focusing on the diagonal distance, or aiming too low by only focusing on the horizontal distance.

How an ACI Works

The ACI (angle cosine indicator) provides a cosine value of the angle of the projected shot. This value is then multiplied with the actual slope distance of your shot. The final value is used to make the necessary adjustment to your rifle scope elevation.

The ACI can be attached to a rifle scope using scope rings to mount it (how to measure scope height?). When it comes to cost, they may be as low as USD 16, or as premium as USD 150. You can consult with your manufacturer to find out which ACI works best for you.

Installing an ACI

You can either install your ACI with scope rings or mounts. The next step is to use a bubble level to level the barrel. Make sure that the ACI is level with the bore, install it, and set it at zero.

When you spot your target, use a laser finder or a reticle with the same feature, and take aim. Then look through the ACI mounted next to the rifle and obtain the cosine value. Use the method described above to get the right distance and make the necessary adjustments to your rifle scope elevation.

Best Scope Mounting Kits – Mount, Level, and Align your Riflescope

Mounting a rifle scope with an Inclinometer or ACI and taking the angle into consideration

Does it Work for Long-Range Shooting?

This method is suitable for short-range shots, but for longer distances of a thousand yards or more, the calculation doesn’t remain that simple. In that case, it becomes harder to attain a value for the slope distance when you’re looking at long-range shooting.

The cosine value is entered into ballistic software, which may be run on a smartphone or tablet. This software looks at the distance the bullet must travel at an angle and the extra time it will take as opposed to covering the same distance in a flat line.

Using ballistic software is more accurate than calculating on your own because it takes into account the fact that different types of bullets have different velocity, coefficients, time and rate of deceleration. It is also faster than manual calculations.

Bubble Levels

Bubble levels assist in long-range shooting to resolve the problem of canting. Canting is the degree of movement of your rifle when you take a shot.

At long range, even a slight cant of a single degree can throw off your aim. Bubble levels help center your rifle and shot, but are generally suitable for flatter terrains.

Can Bubble Levels be used with Inclinometers?

If you’re using an inclinometer on your phone, you can find apps that combine inclinometers with the bubble level. They provide both the options so you can choose what you’re most comfortable with given the range of your shot and the degree of incline/ decline.

Combining the inclinometer with the scope level provides increased accuracy for long-range shooting. Adjustments can be made instantly and reliably and the scope level can become part of your shooting gear to make sure to have rifle and scope aligned when targeting.

Leveling a rifle scope using a bubble level

Using an iPhone as an Angle Degree Indicator Your Rifle

Using Your iPhone as an Inclinometer

The Apple PlayStore for iPhones has apps that can be used as inclinometers. The “Compass” app and others are inbuilt inclinometers and can be used along with ballistics apps, such as KAC BulletFlight or The Applied Ballistics Mobile Application.

Ballistics apps provide features such as:

  • Ballistics engines to run equations of motion
  • Access to the library containing past data
  • Drag curves to account for gravity when shooting at an incline/ decline
  • Profiles for your weapons which contain information about your rifles, sights and optics
  • Bullet Information, which includes a library with information on popular bullets so that you can choose the one you have and find its ballistic coefficient
  • Distance calculator for projected target range
  • The ability to determine the angle of the slope
  • Atmospheric measurements to incorporate factors, such as temperature, wind speed and altitude in the calculations

You can either manually input the angle of the shot or mount your phone onto your scope to avoid any miscalculations or accidentally inputting the wrong value.

Mounting Your iPhone on Your Scope

In order to secure your iPhone onto your rifle, you’ll need a smartphone adapter/mount. Simply attach the adapter to your rifle scope, slip your phone into it, secure it and you’re done. You can get different types of rifle mounts, which are suitable for your phone and the scope you are using.

Make sure your phone has a screen protector and cover to avoid damaging it out on the field.

Using a rifle scope inclinometer

Shooting Has Never Been This Easy!

With the help of devices like inclinometers and ACIs, you can aim easily and accurately, even for shots at steep angles. If you don’t want to get a separate device or have another item attached to your rifle, you can simply use your smartphone for the same purpose.

There are many apps that will do the job. No matter where you are and how steep the surface is, you’ll always be able to aim accurately. In addition, you can and should use a scope level to reduce or eliminate canting and improve your accuracy even further.

How do you use an inclinometer on a scope when you're long-range shooting?
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Aaron Bennett