How to zero a rifle scope

Zeroing your new scope seems to be one of the biggest mysteries out there. There are even special tools that have been invented for this job like fancy laser boresighters and other gizmos, none of which are required to zero a scope. We’ll take you through how to properly zero your scope without any such gizmos, and most likely clear up misconceptions you may have about the topic.

What is zeroing? Zeroing is the process of aligning the point of aim with the point of impact, so that the two become one.

Let’s break this down some more by defining exactly what we mean:

Point of aim: The spot where you are aiming at, denoted as the spot where the crosshairs on your reticle intersect.
Point of impact: The spot where your bullet actually goes.

By looking at these two definitions, all we are basically doing is making sure that the bullet actually goes where we put the crosshairs. Not as complicated as you thought, right? Well there are some wrinkles in the process, the first one being range.

Consider that the trajectory of a bullet is more or less an arc rather than a straight line. When a bullet runs out of steam, it falls to the ground. This part seems fairly intuitive, but most people fail to realize that the moment the bullet leaves the barrel, it succumbs to gravity and begins a downward trajectory. No matter how high powered the cartridge is, gravity always wins, and it hits the ground if it hasn’t hit the target first.

What we are getting at here is that we must zero the rifle at a certain range, and since gravity affects the bullet, the rifle is only zeroed to that range – any other range will require corrective input on the scope by adjusting the elevation knob. This is so earth shattering that most new shooters aren’t even aware of this, and it leads to confusion and more questions. Let’s clear it up a bit First of all let’s talk about the preferred range to zero a rifle (and therefore zero the scope) at. Most military units zero weapons at 300 meters, but that is impractical for civilians as there aren’t always shooting ranges with that kind of distance available. Here is the rule, however:

Zero at the range you intend to engage targets at

It’s really that simple. Do you hunt? What ranges do you anticipate engaging targets? Zero at that range. Same goes for tactical or long range shooting, but there is another dimension there. It would be impractical to zero at 1000 yards because there are so many variables that affect where the bullet goes at that range.

The safe bet for most shooters that are shooting .308 and .30-06 is to zero at 100 meters, as this is an easily obtainable distance. These cartridges shoot relatively flat out to 500 yards, so there isn’t much if any adjustments that need to be made inside those distances. Beyond those distances, simple elevation corrections are dialed in via the elevation turret on the scope.

So how do you zero your new scope? Follow these simple steps:

Pre-Zero at home

1. Mount the scope to the rifle via the rings and bases, if you are using a base system. It’s easy to impart errors into the scope by mounting it slightly crooked! Even though there doesn’t seem to be a lateral adjustment on most scope rings and bases, over torque in a lop sided manner when screwing the top ring down can slightly cant the scope, and a slight error is all you need to throw it off. Be careful here.
2. You will need to make sure that the scope’s turrets are centered, as they are often not centered from the factory. How we check for this is by taking one turret at a time, and turning it all the way in one direction. It doesn’t matterwhich direction you choose, left or right. Either way, start with the elevation turret and turn it all the way over. Then on turn it all the way back, except this time, count the number of clicks it takes until it is hard over to the other side. Write this number down. Divide it by two, and then enter that number of clicks into the turret. This will precisely center the turret. Do the same with the windage turret. Now your crosshairs are perfectly centered, but not zeroed.
3. With the scope now mounted on the gun and with the scope crosshairs centered, and will making sure the rifle is unloaded, take the gun to a place on your property where you can see about a hundred yards away. This can be done outside or it can be done inside while looking through a window. Remove the bolt from the gun, or in the case of a semi auto, separate the upper and lower and remove the bolt carrier group. Either way, you want to make it so that you can see through the barrel.
4. Next, position the gun on shooting bags or within a gun vise, or use the gun’s bipod. Don’t get technical here, just securely brace the gun and point it at a distinct object 100 yards away, like a mailbox, streetlight, tree trunk, whatever.
5. Look inside the barrel of the gun, and center the barrel of the gun on a distinct object.
6. Next, without touching the gun, lift your eye up to the scope. Do you see the same object? If so, is the scope centered on the same object that the barrel sees? If it does, you got lucky. If not, carefully turn the elevation and windage knobs until the center of the crosshairs corresponds to the view inside the barrel.
7. When the crosshairs point to what the barrel sees, you are ready to head to the range – your scope is zeroed enough to at least get you on paper.

Zero at the range

Now your scope is bore sighted, and you should hit paper on your first outing, since the scope is roughly zeroed on the barrel of the gun. Now it’s time to test this at the range. Here’s what you do:

1. Make sure the rifle is securely supported on sandbags or a bipod. Take as much of your body out of the equation as possible by not unnecessarily touching the rifle.
2. Load the rifle, place the crosshairs on the target 100 meters away, and using all of your effort, fire off the steadiest, most careful shot you can.
3. Note where the shot went. Was it high? Was it low? The best way to check this is by actually walking up to the target and looking at it, but that may not be possible at all shooting ranges due to the number of people. A spotting scope or binoculars will do in this case.
4. Carefully look through the scope and place the crosshairs on the center of the target.
5. While holding the rifle steady, turn the windage and elevation knobs so that the crosshairs drift from the center of the target to the hole of the shot you previously made; basically, walk the crosshairs to the hole.
6. Fire another round, aiming for the center of the target. Your shot should be dead on. If not, repeat steps 4 and 5.
7. After the scope is zeroed, remove the windage and elevation turret caps, and per the manufacturer’s instructions, and without turning the turrets any clicks, take the caps off and place them on the zero marks.
8. Your rifle and scope are now zeroed for 100 meters. Fire off a 5 shot group to make sure.

Basically, your rifle and scope are now speaking the same language. Be advised, however, that there are times when this could all change. In fact, your zero changes any time you:

• Use a sufficiently different load of ammunition than you zeroed with
• Use a heavier or lighter bullet than the bullet you zeroed with
• Hold the rifle differently or have a different check weld than you originally zeroed with
• Have a different eye relief than you originally zeroed with
• Shoot at a different range than you originally zeroed with

The rule here is consistency. Be consistent in your shooting, and your scope will stay true.

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