Adding a red dot sight to your weapon of choice is an exciting moment, and you’ll be itching to test it out at the first opportunity. What’s not so exciting is sending your first round down range, and it’s way off target. “Zeroing” your new red dot sight should be the first thing you do once it’s properly mounted. Fortunately, how to sight in a red dot is not the most difficult thing in the world.
The first thing you need to do is familiarize yourself with your new optic. Most optics come with adjustment knobs on the top and side or 12 o’clock and 3 o’clock. The most common adjustment is ½ MOA when zeroing at 100 yards. Every click on either knob will equal ½” point of impact at 100 yards.
Some people prefer to zero their scopes or rifles at 25 to 30 yards, and that’s fine, so long as you know the adjustment value of your MOA and how it changes at 25 yards versus 100 yards. You can also bore sight your red dot optic or use a laser bore sight.
Complete Guide to Red Dot Sights
How does a red dot sight work
No matter how crazy, wild, or lethal your new optic looks, the basic premise of the red dot is pretty simple. A red dot optic isn’t designed for magnification. It’s only a 1x optic with the added benefit of placing a red or green dot over the top of the front sight post.
A single LED light is projected onto a piece of glass that is coated to prevent various other colors from interrupting the red or green dot. The light (reticle) is reflected back to your eye. It’s not projected. You can’t see the red dot outside of the optic.
How to sight in a red dot
Starting with the range, your distance from the target only matters based on your firearm. For a rifle, 100 yards is perfect. For pistols and shotguns, 25 yards will work. Fire three rounds to establish a group. Observe and adjust.
Base your adjustments on the very center of a group of three. In other words, locate your three round impacts on the target and think of them as a triangle. Make your adjustments based on the very center of that triangle.
Some sites assume everyone is a mathematical genius, and they’ll hammer you with formulas and windage adjustments while referring to everything in acronyms. It’s ridiculous. All you need to know is how many inches a single click on your 12 o’clock and 3 o’clock moves your impact.
How to sight in a red dot optic without shooting
Bore sighting and laser bore sighting are the two methods for sighting in your red dot sight without shooting. The latter is easier because the former isn’t always possible, depending on the firearm. You should have a vice for maximum stability, regardless of which version you use.
Bore sighting requires a vice grip because you will have to look down the bore of the rifle, visually mark your target, and make adjustments with the red dot sight until it is roughly in the same spot as your view through the bore.
It requires the target to be pretty close, so you can use visual markers like the bullseye. You want to align your bore so that the bullseye is as close to center mass as you can get. Then switch to your red dot optic and adust until the red dot sits right where you were just looking through the bore.
Laser bore sighting
The concept remains the same, but the accuracy is improved a bit. You need to pick out a good laser bore sight that matches the caliber of your weapon. You simply rack the laser bore sight in the chamber in place of a round. The laser lights up a red dot on the target.
With your rifle stabilized, switch your view to the optic and adust the red dot sight so it matches the projected red dot from the laser bore sight.
No matter which method you use, you need to follow up with live fire to make the small tweaks necessary for a perfect zero. Neither laser bore sights nor a visual bore sight method is perfectly accurate until you fire some rounds down range.
How to adjust a red dot sight
We’ll use the Vortex Strikefire II as an example here, mostly because of its acclaim and its simplicity. It’s a 4 MOA optic with elevation and windage adjustments that equal ½” per click at 100 yards.
Let’s say you fire three rounds and find the center mass of those three rounds is 5” below and 2” left of the bullseye. The equals 10 counterclockwise clicks on the 12 o’clock elevation adjustment and four counterclockwise twists on the 3 o’clock windage adjustment.
The elevation and windage adjustments are usually labeled, letting you know how the reticle is adjusted based on which direction you turn the knob. Be sure to get a good overview of the manual that comes with the red dot sight because it will let you know the MOA of the optic along with the windage and elevation adjustments.
You will need that information when it’s time to sit down and zero in your red dot sight.
How to use a red dot sight
Every optic has its variations, but most of them are designed to line up the red or green reticle directly over the front sight post of your weapon. It’s as simple as that.
- Focus on the target through the optic
- Keep both eyes open
- Place the red dot on the spot you want to hit
That’s all there is to it, although it will take time and practice for you to learn how to quickly acquire your target and fire. For some additional context, every reflex sight is a red dot sight, but not all red dot sights are reflex sights.
For the most part, you probably have a reflex sight, and it’s important to know the difference between the two, especially when it comes to how you aim them. A red dot sight comes in three variations—prismatic, reflex, and holographic.
The reflex sight is a red dot sight that is reflected back to your eye as we discussed above. Holographic sights are typically shaped like a rectangle and do not look like a scope in appearance. The red dot reticle it produces is center mass in a large square, making target acquisition simple and quick.
Prismatic sights use a laser that is already etched into the glass. Some of them come with a low level of magnification, but the eye relief is generally pretty poor. They are the slowest in terms of target acquisition because you have to form a cheek weld and move your eyes up, which takes more time.
The thing you should know about all of the red dot sights is that so long as you can see the red dot, no matter what angle or your eye relief position, your round will strike where the red dot is.
A red dot sight is an excellent tool addition to your rifle, shotgun, or pistol. It’s incredibly accurate and works wonders in low-light situations. It doesn’t take much to zero a red dot sight either, and rapid target acquisition comes with practice and execution.
Red dot sights are superior, in terms of rapid target acquisition, to traditional iron sights, and they are an effective replacement for your glow sights, though you don’t have to remove either from your weapon if you purchase a red dot sight.
In fact, red dot sights are great as a co-witness with your existing iron sights. They take a bit of getting used to, but they’re worth the price and time.
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