To zero a red dot, you fire a small group of shots at a target, measure how far the group sits from where you aimed, and turn the windage and elevation dials by the right number of clicks. Then you shoot again and repeat until the group lands on your aim point. The key number is how far one click moves the bullet, and that comes from your optic’s manual.
This post covers the click math, the distances, the steps and the mistakes. It is general information from optic makers and shooting publications. Use your own optic’s manual for the final numbers. We also cover what we do at the shop before you ever get to the range.
How Does a Red Dot Click Value Work?
Every click moves where the bullet lands by a set amount. That amount is measured in MOA, short for minute of angle. One MOA is about one inch at 100 yards, and it shrinks or grows with distance.
Trijicon’s RMR manual is a clear example. It says one click equals one MOA, which is about one inch of change in bullet impact at 100 yards, or one quarter inch per click at 25 yards. Other optics differ. Pew Pew Tactical says red dots use clicks of a quarter, a half or one MOA, and that most use a half or a quarter. It points you to the manual, the maker’s website, or the markings on the dial.
So the first job is to look up your click value. Without it, you are guessing. The same math shows up in scope guides. NRA Women notes that 1 MOA is half an inch at 50 yards and one inch at 100 yards, so a quarter-MOA click moves the impact about an eighth of an inch at 50 yards and a quarter inch at 100.
| Click value | Change per click at 25 yards | Change per click at 100 yards |
|---|---|---|
| 1 MOA | About 1/4 inch | About 1 inch |
| 1/2 MOA | About 1/8 inch | About 1/2 inch |
| 1/4 MOA | About 1/16 inch | About 1/4 inch |
The 1 MOA row is Trijicon’s own numbers. The other two rows are the same math cut in half and in quarters.
What Distance Should You Zero a Red Dot At?
It depends on the gun.
- Pistol: Trijicon’s procedure uses a 25 yard target.
- Rifle: Pew Pew Tactical starts at 25 yards to get on paper, then uses 50 or 100 yards, typically from a rest or bags.
Closer targets take more clicks to move the group an inch, as Pew Pew Tactical notes, so starting close is a way to get the dot on paper before you refine.
How Do You Zero a Red Dot, Step by Step?
Wear eye and ear protection and treat the gun as loaded at all times, per the NSSF’s rules of firearm safety. Before you shoot, make sure the optic is tight. Trijicon says to torque the RMR’s mounting screws to 15 inch-pounds, and other makers give their own numbers, so check your manual. Then:
- Get a steady rest. Bags or a bench rest take your hands out of the picture.
- Center the dot on your aim point. Trijicon says to fire a precise group of at least three rounds. Pew Pew Tactical says three to five.
- Measure the group. Find the middle of the group and measure how far it is from your aim point, left or right and high or low.
- Do the click math. Divide the distance by your inches per click. Pew Pew Tactical’s example: at a half-MOA click value, a 3 inch offset at 100 yards takes six clicks. At 25 yards with a 1 MOA click, using Trijicon’s quarter inch per click, a 2 inch offset takes eight clicks.
- Turn the dials. Follow the arrows on the dial or the manual.
- Shoot again. Repeat until the center of the group is on your aim point.
- Let the barrel cool between groups. Pew Pew Tactical lists this in its steps.
Trijicon says that once the group is centered, you have set the point of aim as the point of impact for that gun.
Three habits make this go faster. Shoot a group, not one shot, because Trijicon asks for at least three rounds. Rest the gun, so the group shows the sight and not your hands. And change the dials only after you have measured, so you are not chasing every flyer.
Which Way Do You Turn the Dials?
Check your manual, because makers differ. On the RMR, Trijicon says turning the elevation dial counterclockwise moves the dot down, which moves the bullet’s impact up. Turning the windage dial counterclockwise moves the dot left, which moves the bullet’s impact right. That is Trijicon’s design. Another optic may be set up the other way.
What If Your Rifle Also Has Iron Sights?
If you use iron sights and a red dot together, there is an order. Pew Pew Tactical’s co-witness guide says to zero the irons first with the optic off, then install the optic, confirm the sights work, and fire a few rounds with the dot off. Then adjust the dot to sit on the front sight tip and confirm the zero with the dot alone. The dot may seem to shift with your cheek weld, which the guide calls normal.
If your rifle has an absolute or a lower one-third co-witness, our post on red dot co-witness explains each one. For the irons themselves, see how to adjust iron sights.
When Do You Need to Zero a Red Dot Again?
Every time you change a variable. Trijicon says an optic moved to a different firearm needs a new zero. NRA Women says to re-sight when you change ammunition, including brand, bullet type or weight. Their advice is for scopes, but the logic is the same for a red dot.
What Does Lakeside Do Before the Range?
We do not have a range at our shop, so zeroing with live rounds happens somewhere else. What we can do is get the optic on the gun right.
Our posted price for an optic mount is $45, red dot or magnified, on our gunsmithing price list. If you buy the optic from us, we install it for free. If the optic goes on a pistol slide, call before you come in so we can tell you what we can do for that gun. Bore sighting is $15, which helps a rifle’s optic get on paper so you waste fewer rounds. See our post on how to bore sight a rifle for what that does and what it does not do. Posted prices are for a firearm in factory condition. If other changes have been made, we look at the job first.
When the red dot is on and you want to get to the range ready, read the gunsmithing page or contact us with your gun and your optic.
