For the most part, mounting a rifle scope is pretty easy. There’s nothing especially difficult about situating a scope properly in a mount or set of rings, or torquing it down properly, provided you have the right tools. It’s a very manageable task, even with the added step of attaching a scope base for bolt-action rifles. But getting it level—especially if you want accurate tracking out to a thousand yards or more—can be a bit tricky.
Below, we’ll take a look at common myths regarding rifle scope leveling, as well as the two most popular methods to properly level a scope.
Rifle Scope Leveling Myths & Mistakes
There’s a lot of bad advice out there regarding scope leveling. Much of it stems from the fact that for most applications, a sub-par leveling job isn’t all that noticeable or detrimental.
If you only ever shoot your firearm out to a hundred yards, you’ll likely never notice if your crosshairs aren’t perfectly squared to your rifle. Even at a few hundred yards, the effect on rifle scope adjustment and drop compensation is minimal unless the leveling error is dramatic. It isn’t until you start trying to push your firearm out to longer ranges that the flight path of your bullet starts to significantly diverge from your reticle.
One of the common erroneous leveling “tricks” is to use a telephone pole or fence post as a point of reference when mounting your scope. While these everyday items might appear perfectly vertical to the eye, they rarely are.
You may also hear that leveling using a bubble level or angle cube is insufficient and that only plumb bob leveling can achieve a truly squared reticle.
This claim may have been true once, but is now mostly outdated. In years past, it was not uncommon for budget and even midrange scopes to have reticles that were not perfectly square to the turrets, which are used as a reference point when leveling using a bubble or scope level. In modern optics, though, the reticle can generally be trusted to be perfectly straight within the optic itself.
Rifle Scope Leveling: Bubble Level Method
This method is probably the easiest and most straightforward, but unfortunately, it doesn’t work with all rifles. To level your scope using the bubble level method, you’ll need a squared, flat section on your rifle. For AR-15s and similar firearms, the upper Picatinny rail works perfectly. Some rifle scope mounts even have a bubble level built in, which can make this process a breeze, although you will need to manually verify that the mount is level with the rifle before relying on it.
To level your scope using a bubble, start by securing your rifle in a rest or vice that be adjusted to make it level. Some rests have this feature built-in; others can be leveled using shims. Place the bubble level on the rail of your rifle when leveling—ideally on the receiver, though in most cases the handguard will work as well.
Once your rifle is level, place your scope in the mount or rings and situate the bubble level on top of the elevation adjustment turret. You can then proceed with mounting your scope, checking frequently to ensure your scope remains level.
It is advisable to also move the bubble level back to the rail of your firearm periodically, to ensure it has not shifted. If you have multiple bubble levels, you can place one in each location to make the process easier. Once mounting is completed, both the scope and rifle should be checked one last time to ensure they both remained level throughout the process.
Alternatively, an angle cube can be used to make the process even simpler. Angle cubes are essentially digital levels. Because they can be placed on the rail of the rifle and then zeroed, they negate the need to precisely level the rifle. Simply placing the angle cube on top of the turret of the scope and mounting it while maintaining that zero will ensure the scope is trued to the rifle.
Rifle Scope Leveling: Plumb Bob Method
Plumb bob leveling is the oldest and most reliable method of leveling a rifle scope. It’s also the most time- and tool-intensive, and to be done well requires a fairly large open space in which to work. But, it will also work with pretty much any rifle, while the bubble level method is limited to rifles with a flat surface on which to place the level.
As with the bubble level method, you’ll want to start by securing your rifle in a rest or vice. Then, level it in the same manner as previously described. The plumb bob can be used as a reference by hanging it behind the stock and adjusting the rifle until it is perfectly vertical.
Now that the rifle is level, hang the plumb bob in front of the rifle. The distance from the muzzle will be determined by the type of scope you are mounting—the more magnification your scope offers, the farther away you will often need to hang the plumb bob to be able to focus on it.
For many scopes, you’ll want to hang it at least 25 feet away. Further is often better, up to the parallax setting of your scope. If your scope has a parallax adjustment knob, dial it down to the lowest setting and hang the plumb bob as close to that as possible. Most fixed-parallax scopes are factory set at 100 yards, so just hang the plumb bob as far as possible for those.
Once the plumb bob is hung, you can go through the usual process of mounting a scope, using the line of the plumb bob as a reference to keep the vertical stadia of the crosshairs in your scope trued to your rifle. It’s important to keep checking your scope’s verticality during and after the mounting process, as tightening the screws on your scope rings can sometimes twist the main tube, although this can usually be avoided by tightening each side evenly in an alternating pattern.
Ultimately, there’s no one “correct” method to level a rifle scope. Both of these methods are capable of producing a perfectly level scope with crosshairs trued to the actual flight path of the bullet.
For bolt action rifles that lack flat surfaces on the receiver, a plumb bob is generally the best method for leveling a rifle scope. For AR-15s and similar firearms, a bubble level or angle cube can often be used to make the process faster and easier, but using a plumb bob will still result in a level scope.