When people talk about “scope leveling,” they generally mean setting up a scope such that the vertical or “Y” axis of the reticle is exactly perpendicular to the rifle stock.
If you’ve used products like the Wheeler Professional Grid Leveling System, you’re familiar with this exasperating and time-consuming process.
However, “range leveling” can also refer to leveling a reticle to the ground during the firing process. When the term is used in this way, it does not matter whether the scope is level with the rifle or not. All that matters is that the reticle is level with the ground when the user pulls the trigger.
You can assume that these concepts can be used interchangeably. If you did, you would be like me, and like me, you would be wrong. It turns out that the latter process is much, much more crucial than the former.
You need a level grid
A reticle that tilts even a few degrees during the firing process can deflect a shot by several inches, sometimes even several feet, depending on the distance of the shot, Nick Laufenberg told me. Laufenberg is a competitive long-range marksman and the sniper rifle specialist for the Vortex optics company.
However, if the scope is installed crooked but the shooter “levels” the reticle before pulling the trigger, the shot will still hit the target.
“If you have the optic tilted one degree on your rifle, but it is level when you are zeroing it (ie you tilt the rifle to achieve a level reticle), then you will see less change in the horizontal point of impact. than if you have the scope level with the gun but you don’t tilt the entire gun one degree when you shoot,” Laufenberg said.
In other words, a canted scope can be installed and still produce good shots as long as the reticle is level with the ground when the user shoots. While misalignment of the reticle and rifle can introduce some horizontal drift, it’s “minimal” compared to a reticle that tilts while firing, Laufenberg said.
In fact, Laufenberg told me he knows competitive shooters who set their scopes askew on purpose to compensate for the way their body naturally holds the rifle. The scope is not level with the action, but when they are positioned behind the rifle to fire, the reticle is flush with the ground.
How this matters in the field
At this point, you’re probably asking yourself the obvious question: So what? How does scope leveling affect shooting in the field?
Laufenberg gave me an example. At 500 yards using a .300 Win. Mag, two degrees of tilt moves the point of impact horizontally 17.6 inches. That’s more than enough to miss or hurt an animal, and displacement increases with distance.
To take an example you’re more likely to find in the field: At 300 yards with a 6.5 Creedmoor, the horizontal movement would be 8.6 inches at a two degree tilt.
Two degrees of cant isn’t much, and Laufenberg said most people have trouble capturing two degrees on flat surfaces. On uneven surfaces, like the ones we often find in the field, five degrees is usually when people start noticing that their reticle is crooked.
If you want to do the math yourself, here’s the formula. Again, this formula describes the offset when the reticle is tilted over the weapon in the field. Produce answers in MOA:
Vertical: Quadrant adjustment in MOA + 3 * cosine of bank angle
Horizontal: Quadrant adjustment in MOA + 3 * sine of bank angle
For a longer discussion and more examples, check out Vortex’s coverage of this topic here.
How to overcome a crooked scope
Laufenberg suggested several ways hunters can ensure they have a level scope and rifle.
First, using the retention marks on your reticle often provides enough visual information to identify a tilted scope. If you are using your remaining furlongs and see that the center of your crosshair is to the left or right of your target, you know your scope is not level.
These bubble levels will also provide that feedback. They connect to your scope tube and, if installed correctly, can verify that you’re shooting straight before you pull the trigger.
Laufenberg mounts his rifles by leveling the scope reticle with the picatinny rail. He then installs a spirit level and checks its position using a level on the top turret of the scope. Once he has the spirit level tightened most of the way, he uses a screwdriver or other small tool to align the level.
I do not want to exaggerate the importance of this topic. At close ranges, the effects of a tilted scope and rifle are negligible, and most hunters know intuitively that a reticle must be level before the trigger is pulled.
Still, I was surprised by the math. Especially for Western hunters, who often shoot long distances in mountainous terrain, it is worth taking steps to ensure a level reticle. Those spirit levels are only about $40, but they could mean the difference between a missed shot and a downed animal.