If you’ve been using a rifle scope like for example the Nikon Prostaff scopes without a bubble level attached, you’ve truly been missing out. Bubble levels, attached to your rifle scope, offer precision and accuracy that cannot be matched by levels found on regular rifles. The bubble moves at a very slow pace and it is crucial to check the level before pulling the trigger. They also can be helpful when you are initially mounting the rifle scope to ensure that everything is lined up.
What is an Anti-Cant Bubble Level for a Rifle Scope? It’s a device that you attach to your rifle scope to ensure that the scope and your rifle are leveled. Otherwise, you can experience what is known as a cant error.
Check out our reviews of the top-rated scopes for ranges of 500 yards!
What is the Main Purpose of the Level?
The position of the scope on your rifle is adjustable so that your projected impact point is at par with the targeted point. Moving your weapon around will still keep your target within the crosshairs of your lens, but your scope will no longer be aligned with the barrel of your rifle. This leads to a phenomenon known as cant error.
The Cant Error
What is Cant Misalignment?
Let’s start off with some basics. When we’re target shooting, the projected movement of the bullet takes into consideration the vertical pull of gravity.
Practically speaking, if two bullets of different weights are fired through the same distance, they will hit the ground at the same time. The difference is that the heavier bullet will travel a greater distance. The lighter pellet will need greater elevation during the firing process to balance out the difference.
This is a concept known as elevation compensation. Rifles come with a sighting device to calculate the amount of elevation compensation required. The elevation compensation required is typically more of a factor for long-range shooting.
In order to have a smooth trajectory of your aim, the scope and the rifle must be parallel to each other. This means that if you move your rifle to a better angle, you must also adjust your scope accordingly. – Learn all about the different adjustments on your rifle scope here!
You can adjust this angle with the help of your rifle’s scope optics. When the rifle and scope are no longer parallel and are at an angle to each other, cant error occurs. This results in a cross-over between your projected trajectory and your actual line of sight.
Have a look at our review of the Leupold Mark 3HD riflescopes!
Cant is more important when shooting long-range. Here’s our reviews of the best scopes for long-range like 1000 yards.
Canting Your Rifle
Cant is basically a fancier term for tilting a weapon during the shooting. There are some basic steps you can follow to prevent this from affecting the accuracy of your aim.
Step 1 – Ensure the position of the Reticle Crosshairs
Ensure that the crosshairs on the lens of your scope are at a 90-degree angle to the bore (the barrel of your rifle). It is essential to do this at the beginning since getting the right position of the crosshairs is generally a trial and error process of shouldering the weapon, looking through the lens, and adjusting till you’re satisfied.
Preventing Cant Error: During this adjustment phase, it is likely that you will end up overlapping the crosshairs with the bore of your rifle. There’s a simple fix for this. Keep your gun clamped with the help of a level fixture before aligning the crosshairs according to your target.
Step 2 – Level the Scope out in the Field
Step 2: When you’re out on the field, you are likely to use a tree branch or a stone or something of the sort for support. While these surfaces may be sturdy, they are generally not leveled. This can also cause a cant error. Look for a perfectly leveled plane of reference (it may be horizontal or vertical) and level your gun accordingly.
If you use a bipod then you might have a better chance of being level from the get-go. However, if you position the bipod on a rocky surface you sill will end up not being level and needing to adjust as outlined in Step 2.
Using an Anti-Cant Device for Leveling
If you’re serious about the sport, having an anti-cant device fitted on your rifle is essential. The first and most important piece of equipment required is a good quality anti-cant bubble level for your rifle scope tube.
The quality of your rifle will also affect how well your bubble level works to get rid of the cant error. The markings on the bubble level indicate the degree by which your angle is off from the desired perpendicular angle.
Different Types of Anti-Cant Devices
Anti-cant devices are of different types with some that attach to your scope tube and others that attach straight onto the rail of your rifle. Just bear in mind that leveling is essential for a serious shooter, especially for long-range shooting. To successfully level your scope you need to use an anti-cant device and you will see significant improvements at long-range shots.
If you haven’t leveled your reticle, it’ll always be a mystery whether your missed targets on long-range shots are due to alignment problems with your reticle or a freak wind, or a sudden change in weather conditions. Your long-range shooting will improve tremendously when using anti-cant devices.
Check our reviews and recommendations for the best 30-06 scope
Level a Scope
Make sure you do some research before you buy your anti-cant bubble level. Keep in mind the type of rifle you have and the type of hunting you frequently engage in (short or long-range). If you’re unsure, consult a professional.
Once you got your anti-cant bubble level, it’s time to actually mount it on your scope – have a look at the best riflescope mounting kits here. Start off by tying a bobble to the end of a piece of string and let it hang vertically downward.
Keep it at a slight distance from the scope to avoid blurring the string out due to magnification. An ideal range is to keep the string at a distance of around 50-100 meters.
Use a surface to rest your weapon on and level your scope’s vertical crosshair to match that of the string (Pro tip: use colored string to make it easy to differentiate between the crosshair and the leveling string).
Once the two are aligned, adjust your anti-cant devices to read level and make your scope level. This is what will calibrate your leveling device to your scope’s reticle.
Standard anti-cant bubble-levels have lines on either side to depict when your weapon is level. Adjust your anti-cant device so that the edge of the bubble meets with one of these lines so that you know exactly when your device is level.
Leveling your Reticle
You can adjust the level of your scope during your hunt by adjusting the eye relief on a scope. If you are interested in canting your reticle, ensure that it is aligned with your anti-cant devices.
Don’t cant your rifle too much as this can cause disturbances between the alignment of the axis of your scope and the bore of your rifle. Just make sure you level your reticle before taking aim with the help of your anti-cant devices.
The Vortex Crossfire II is one of the best scopes around. Have a look at the in-depth review!
Why Canting is Important
If you’re blaming every missed shot on a sudden and unexplained wind, the problem is with you and not strange weather. Every trained shooter knows that they must keep a certain wind speed and direction in mind before shooting.
If your cant is off then your wind adjustments and holdovers will be inaccurate. Adjusting the cant of your rifle with the help of an anti-cant device and keeping a fixed wind call will allow you to meet your mark.
Leveling your Scope
One way of leveling your rifle and scope setup is by adjusting the tripod or bipod stand of your weapon. This will work perfectly well for target shooting when you have time. When you’re out on the hunt, you may not have the time to make such adjustments.
Even though it takes a bit of experience, it’s best to be able to understand the cant of your rifle and adjusting your hold on your weapon accordingly. It takes a skilled eye to identify a cant, which is of 5 degrees or less. This is particularly true for uneven and hilly terrains.
Best Scope Bubble Level
A quick search on the internet will be sufficient to show you that there are countless different types of levels available on the market. The accuracy of each bubble level definitely varies.
List of the Best Anti-Cant Devices for your Rifle Scope
The following short reviews provide you with some in-depth information on the best bubble levels you can get today.
We looked at a variety of different scope bubble levels and found that the best so far are:
Vortex Optics Riflescope Bubble Level
The Vortex Optics Riflescope Anti-Cant Bubble Level is designed to be mounted on the rifle scope tube. It has a bubble that makes it easy for you to level your rifle, so you can enjoy using your scope without worrying about any unwanted misalignment of the crosshair. The bubble levels from Vortex are available for scopes with tube diameters of 1 inch, 30 mm, 34 mm, and 35 mm.
Mounting the Vortex bubble level is straightforward. Vortex made the lower part of the clamping ring mechanism thin enough, so it’s easy to slip between the scope and the base/rail. In most cases you will not even have to take the scope off to mount the level.
A great feature of this anti-cant device is that the air bubble matches roughly the distance between the two lines. This makes it easy to precisely level the scope and avoid any targeting errors from canting.
The device is visible all the time. If you aim with both eyes open, then it can be in the way. This setup works well if you need to adjust the cant for every shot, as you can clearly see the bubble at all times.
A design that allows folding the bubble away when not needed is in some cases desired. When you use a bipod or use a bench to rest your rifle on to take many shots, you usually need to align the scope and rifle only once to eliminate canting. After that, being able to fold the anti-cant device away allows you to have a clear view and easy access to all turrets of the scope.
The clamp and bubble housing is made from machined aluminum. Vortex added a protective finish to prevent easy scratching of the device. Using aluminum makes it reasonably lightweight, so it won’t get your rifle out of balance.
It’s hard to find something genuinely wrong with the Vortex anti-cant device. It’s built solid, allows for quick reading of the bubble, and can be mounted on practically any scope you can get. On top of that, it’s affordable. Due to all that, it’s our overall top pick as the best rifle scope bubble level.
US Optics Swivel Anti-Cant Device
The US Optics Swivel scope bubble is a rail-mounted anti-cant device. Not only is it mounted onto the rail, but it also has a swivel design.
A nice feature is that the level comes with a screw-on cap to cover the glass vial with the bubble level. This comes in handy when you’re in the field as it protects the level.
The US Optics Swivel anti-cant device is built sturdy and with high-quality aluminum. It’s light and does not have a significant impact on the balance of your rifle.
One gripe we have is that the level itself is a little small. It can be hard to read the device to avoid canting when you’re trying to aim quickly. We like the non-swivel design of the Vortex level or any other one better when hunting. The swivel design requires to position the level to level the rifle, acquire the target and aim, breathe, and shoot. You first have to straighten the level out, and then you can level and so on. That can take too much time when you’re out hunting.
The mounting on the rail provides a sturdy connection between the rifle and the level. You can easily screw the base onto your Picatinny rail. You also do not have to worry about the scope tube diameter when you mount the level.
The rail-mounted design has advantages as it sits tightly and securely on the mounting rail. However, you have to be careful to find the correct spot so your ejected shells won’t collide with the level.
We like the quality of the US Optics Swivel Anti-Cant level. It works great for long-range target shooting. The design, in our opinion, does not work as well as a fixed level like the Vortex one when you’re out hunting and need quick target acquisition and level validation.
Wheeler Engineering Anti Cant Indicator
The Wheeler Anti-Cant Indicator has a bubble level that can swivel out of the way. The mounting point is the scope itself, though, and not the rail.
The level swivels in one direction only. The Wheeler Engineering Bubble Level is available for scopes with a tube diameter of 1 inch or 30mm.
The clamp itself is thin enough to mount it around the scope tube without removing the scope. The top of the clamp is not a solid piece of aluminum to save some weight.
The device is built with high-quality aluminum. It is made with precision parts, and the design ensures that the bubble level provides you with repeatable readings.
Wheeler added a spring that secures the level in either the folded in or out position. It makes sure that the level repeatedly is positioned correctly so you can get accurate readings. The glass vial is large enough to get a good reading.
Like the US Optics device, you can run into issues with ejected shells and potentially hit the level. This is less common, though, as the mounting point is the scope and not the rail.
We like the Wheeler Anti-Cant Device a lot. It has a great mechanism to swivel the level in and out. In our opinion, it’s superior to the US Optics level as it’s easier to read, and the swivel mechanism repeats more exactly. On top of that, it’s also more reasonably priced.
MK Machining Ultra Low-Profile Scope Level
The MK Machining Scope Level is similar to the Vortex Bubble Level. There are some small yet interesting differences, though.
The level has a truly low profile. The ring wraps easily around the scope tube. It has a hinge design, so you only have a bolt on one side of the scope, making it easy and fast to mount and unmount the level.
MK Machining offers the level in three different sizes. It can mount on either a 30 mm, 34 mm, or 36 mm scope tube.
The bubble and vial are easy to read. The build is compact enough that the level is barely in the way when aiming with both eyes open.
The scope level is milled from high-quality aluminum. The black anodization blends the anti-cant device with the typically black scope to give it a coherent look.
We are torn between recommending the Vortex or the MK Machining bubble level when you’re looking for a scope-mounted option. Both are excellent devices that will make sure that you’re not having any cant when shooting. They work great for hunting and long-range target shooting alike.
The MK Machining anti-cant device has overall better protection of the leveling vial as the aluminum is surrounding it. However, we feel that the bubble has a little more space between the lines, making it a little harder to level your rifle and scope. But that’s subjective on our side, and after using both levels for a while, you’ll have no problem leveling your setup whether you pick the Vortex or the MK Machining level as your anti-cant device.
All of the above-mentioned anti-cant devices will allow you to transpose the image of your scope level and reticle together. This will help you avoid wasting time repeatedly lifting your head above your scope to adjust your level.
Prevent Cant Errors without a Scope Level
If purchasing an anti-cant level is out of your budget, you can prevent cant errors from ruining the accuracy of your aim by looking above your scope and adjusting your rifle’s top turret so that it’s in line with the horizon.
Remember, if you want to have an enjoyable shooting experience, you want to be able to aim properly. Take your time in picking the perfect anti-cant scope level so that your aim is on point every time.
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