How to Use a Red Dot Sight (Full Instructions & Photos)

If you’re new to red dot sights, you might have questions you are embarrassed to ask.

Worry no more!

Every question is worth asking when you don’t know the answer including, how do you use a red dot sight?

Overall, using a red dot sight is an undemanding and straightforward process. It’s easy to use as you put an aiming dot on a target and fire. Unlike iron sights that requires lining up three focal planes, it’s as simple as point and shoot with a properly zeroed red dot sight.

Consider the following guide a complete and comprehensive know-it-all including tips for using a reflex or RDS, what you can use with it, how to sight-in a red dot, and so much more!

How to Use a Red Dot Sight (RDS)?

The gist is to keep it simple. Keep both eyes open throughout the entire process. Lift your weapon into the firing position. Put your eyes and dot on the target. Switch your firearm off safe and into fire. Engage target.

Helpful Tips to Remember:

1. No Need to Align Dot with Sights

If your dot is working – use it! Ignore the iron sights.

2. The POA is the Same as the POI

To acquire perfect alignment between front and rear sights, you must have a consistent head/eye position behind them every time. A properly zeroed RDS allows for POA (Point of Aim) to be the same as POI (Point of Impact).

This concept remains largely true regardless of where the dot is in the viewing window thanks to the commonly accepted definition of “parallax free” optics, i.e., red dot sights.

3. Keep Both Eyes Open

This is how red dot sights are intended to be used as this technique improves situational awareness and maintains maximum peripheral vision and FOV (Field of View). Keeping both eyes open can also increase speed.

4. Understand Your Equipment

Read the manual to familiarize yourself with the ins and outs of a specific RDS. Know how the buttons function and freely use the illumination for the conditions. Normally, it’s kept dim for most purposes, including low light, and increase the illumination for bright or snowy conditions.

Know how your rifle performs with the loads you intend to use with the optic. Practice at various distances and train yourself with how you will use that rifle and optic combo. Example, if you’re using a sight with Auto-Off, practice hitting a button as you reach for your rifle.

5. A Properly Zeroed RDS can Serve Long Ranges

Generally, 100 yards and beyond is considered long range for a rifle RDS while 50 yards and beyond can be considered long range for a pistol RDS. Though intended for excellence inside 100 yards, an RDS can be effective for greater distances given that the firearm is capable of doing so.

However, a properly zeroed RDS can serve long ranges. One that is zeroed for 50 yards may serve at 200 yards.

For example, the ballistic data below for a .223 cal. 62 gr. 2900 vel. load calculated by Hornady’s ballistic calculator shows that a zero for 50 yards is accurate at 200 yards. However, the issue between how effective you are without magnification and considering your shooting skills, etc. will determine overall accuracy.

How to Use a Red Dot Sight with AR Iron Sights?

They’re independent sighting systems. There’s an instinctual need to have a back-up in all scenarios and when you’re using a red dot, the AR iron sights serve as a fail-safe. However, iron sights alone can be difficult to see for those with ageing eyes or other vision conditions. Enter here, the RDS.

I would recommend that iron sights are there for the purpose of being a back-up if the RDS fails, not to be used in tandem. Trying to use them together can complicate matters and defeats the purpose of fast target acquisition and having an RDS to begin with. Don’t overthink it.

1. Turn off the red dot sight or remove it from the firearm.
2. Zero the iron sights.
3. Flip down sights or ignore them.
4. Mount the red dot sight and activate the dot.
5. Zero the red dot sight (instructions below).

Don’t waste your time or ammo trying to get the dot perfect on the front sight. Even if one system is setup to verify the zero of the other, it still doesn’t mean that the dot is going to be perfectly aligned with the front post. Is that going to bother you? You’re overthinking it.

Keep it simple and as accurate as possible by zeroing each system independently. You could possibly get in the ballpark of a zero by aligning the red dot with iron sights, but adjustment tweaks are likely needed. A surefire confirmation of a RDS zero is to zero the dot independent of the sights.

To learn more about the advantages of each sighting system, check out our comparison of red dot sights and iron sights here.

How to Use a Reflex Sight with Pistol Iron Sights?

In general, it’s a different world when it comes to pistols. But the concept of using iron sights as a backup system and using a red dot as the primary sight remains true. Red dots can fail, and they need batteries, so iron sights on a pistol are still needed.

Stock sights on pistols tend to be too short to be seen with an RDS. Taller sights may be needed. However, taller suppressor-height iron sights are an after-market purchase, and they are usually at a height to provide an absolute co-witness which can negate the advantages of a RDS in the first place.

Opting for non-distracting, minimalistic iron sights with a lower 1/3 co-witness to keep the FOV clear is recommended. Just like on a rifle, let the iron sights be iron sights and the red dot sight a red dot sight.

How to Use a Red Dot Sight with a Magnifier?

In general, the benefits of a magnifier behind a red dot sight are many. For some, it can improve visual acuity of the dot, and for all, it enhances target visibility and may improve accuracy to some degree.

The best magnifiers are simple in that they provide fixed magnification, have integrated quick-release, flip-to-side mounts, and they have a diopter to allow for some visual compensation. Additionally, they have elevation and windage adjustments.

1. Mount the magnifier behind the red dot sight. You may need to move the RDS further forward on the upper receiver (but not on the handguard) to make room.

2. Due to the very short eye relief of magnifiers, this may take a few attempts at remounting to find the best position.

3. Flip the magnifier into the “engaged” position, if not already, and activate the RDS.

4. Use the diopter if needed, i.e., if the dot is unreasonably blurry or fuzzy or if you need minor compensation for refractive vision conditions, ex. near or far-sighted.

5. Adjust the elevation and windage turrets on the magnifier. These adjustments do not affect the zero on the red dot sight. They only allow movement of the dot as seen through the magnifier to bring it into the center of the FOV.

6. Shoot groups with the magnifier and without to ensure there is minimal to no shift. Usually less than 1 MOA shift in POI between the two is regarded as acceptable.

7. Flip the magnifier into the “disengaged” position when magnification is not desired.

How to Use a Red Dot Sight with Night Vision?

There are various night vision devices that can be used with reflex sights, but effectiveness will vary between setups and user-practicality and skill. Compatible gear includes rail-mounted devices and helmet-mounted NODS.

Night Vision Monoculars

Helmet mounted: One of the best ways to use these with a RDS is to align it for the non-firing eye. Use the firing eye with the RDS on daylight illumination (low enough not to bloom) or else the eye won’t pick up the dot. Be sure not to use the monocular eye for looking through the RDS.

Theoretically, keeping both eyes open allows the images to be superimposed granting night vision and seeing the dot on the target. This can be effective with practice and some alignment tweaks.

• RDS tip: Don’t worry too much if the dot looks unfocused.

• Helmet-mounted tip: Align the monocular as necessary so that you’re not getting double vision, i.e., double images. Additionally, you’ll want to align it, regardless of what eye it’s on, so that you can acquire as close to a consistent position and stance as you would normally shoot without NV.

• Handgun tip: It could be an issue having the NOD mounted to the non-firing eye as you raise the handgun and RDS to your dominant firing eye. This can be remedied, but if mounting the NOD to the dominant eye is the route that is taken, put the RDS in NV mode.

• What about night sights? For handguns, tritium night sights or fiber optic sights may not prove to be beneficial with NV. They can be distracting or blooming, and focusing iron sights with NODS may be difficult, slow, and ineffective. Black sights are recommended.

Rail mounted: It’s likely only rated up to 5.56mm calibers. Usually, manufacturers will advertise if it can handle more recoil. The monocular is mounted behind the RDS. Normally, a mount must be purchased separately for mounting to a rail. Don’t forget, the RDS must be in NV mode.

Night Vision Goggles

Biocular goggles, like the PVS-7, are big and bulky and are used with IR lasers for aiming and shooting with night vision. Binocular goggles with 1x magnification, like the PS31 and the ANVIS-9, you can look down the RDS on a handgun and on a rifle having mounted it forward.

With independent dual tube housings, the option is there to lift one tube to run it like a monocular.

Of note, Teledyne FLIR won a US Army contract to manufacture FWS-I sights. The FWS-I is an incredibly advanced, all-superior thermal gunsight that connects wirelessly to an ENVG-B (Enhanced Night Vision Goggle-Binocular) to provide picture-in-picture RTA (Rapid Target Acquisition) benefits.

This is a game-changing, genius, effective way to do it!

Night Vision Clip-Ons

Clip-on systems are designed for use with riflescopes. They are mounted directly in front of the scope on the rail or mounted via a ring adapter to the objective lens. However, one might ask if it will work with a red dot sight - it would be an improvised setup at best.

Things to think about:

• Other than being limited to only having NV through your rifle aiming system, shields keep out light between the clip-on and scope but wouldn’t work with an RDS. This could be less of a concern if you were only using this setup in dark conditions.

• Recoil resistance. Some clip-ons may only be recoil resistant up to 5.56mm or .308 calibers.

• Since the clip-on is in front of the RDS, what is seen through the sight will be a very small screen. One way to remedy this is to throw a magnifier behind the RDS (got enough room on your upper receiver rail?). This may also address, in an indirect way, the issue that clip-ons are usually designed to work with some level of magnification. However, an even narrower FOV is usually the result.

• There are clip-ons that are collimated for use with magnification as minimal as 1x, but then you’re looking at a $10,000 clip-on. If you had that kind of cash to burn, you could definitely afford to buy a NV scope as a clip-on is usually more expensive than a scope.

• Finally, accuracy. Though clip-ons don’t require you to re-zero your scope, or in this case a red dot, I’d still check and see how well you do.

Why Should You Use a NV-Compatible RDS?

Daylight illumination is bright for an NVD. The IIT (Image Intensifier Tube) is extremely sensitive to light. Daylight illumination may elicit auto shutdown or cause the image to bloom. Though there may be no initial, ill-seen consequences, it may cause possible damage to the IIT in the long run.

NV-compatible illumination settings in a RDS shouldn’t be visible by the naked eye but can be seen with an NVD. These extremely dim settings are deemed safe for use with IITs.

Reflex sights typically have 1-4 NV-compatible settings whereas holographic sights have up to 10 settings.

Do Red Dot Sights and NV Really Work?

In whatever setup is chosen, the red dot can be seen superimposed on the target. Now as to how much POI error exists, practicality issues, and alignment, focus, and collimation problems arise, the obligation is with you to remedy them.

Generally, IR lasers are used in conjunction with NVDs in the military and among LEA. However, there are many legalities involved and the onus is on you to understand them.

For specific laser laws in the U.S., check out CFR (Code of Federal Regulations) Title 21 Section Mark 1040.10 and 1040.11.

Zeroing Your Reflex or Red Dot Sight

Overall, the recommended advice to zero an RDS is to follow manufacturer instructions. However, zeroing a red dot sight is a universal process and is much the same as sighting-in a riflescope. Red dot sights normally have elevation and windage turrets set for adjustments in 0.5 or 1 MOA increments.

Below is a perfunctory refresh of the RDS zeroing process. For more detailed instructions, see our complete How to Zero a Red Dot Sight guide.

1. Mount the RDS and Boresight

Boresighting beforehand can get you on paper and closer to the POA saving on time and ammo. This is done for a close-range distance, usually at either 10, 15, or 25 yards. A fast method is with a laser boresighter. They’re relatively cheap, and in-chamber boresighters tend to be more accurate.

You can always opt to do this manually on a rifle. Take out the bolt on a bolt-action rifle or separate the upper from the lower and remove the charging handle and bolt on an MSR (Modern Sporting Rifle i.e., AR-15). Look down through the bore to center the target.

Once you have either a laser point on a close-range target or the bore centered on a target, move to the RDS without disturbing the firearm. Match the dot to the center of the target using the turrets on the red dot sight.

Reassemble your rifle.

For more on boresighting, both manually and with a laser boresight, check out our step-by-step guide to boresighting here.

2. Zero the Red Dot Sight

For rifles, 25 yards is a good starting point while 5 yards is recommended for handguns. Use sight-in targets that are gridded for faster and easier zeroing. Uncap the turrets if necessary and fire a round to the target.

Calculate how far off the POI is from the POA.

Make elevation and windage adjustments appropriate for the distance and adjustments required.

If you know how to do this, skip to Step 3. Otherwise, here’s a brief on how to calculate and make adjustments.

Knowing that 1” is approximately 1 MOA at 100 yards, we can calculate how much MOA adjustment is required. Since red dot sights typically come with either 1 or 0.5 MOA adjustments, it’s a relatively uncomplicated process.

Here’s an example: I set up at 25 yards. I aim for the bull’s-eye. I hit 1 ½ squares down. I’ll call it good on windage (right/left). The sight I’m using is an EOTech EXPS3-0 that has adjustments in 0.5 MOA.

(example continued below formulas…)

Example continued...

Now knowing these formulas, I know that:

• 25 yards (where my target is) / 100 = 0.25” ← 0.25” is 1 MOA at 25 yards.

• Next, I know that I am 1.5” low / 0.25 (which is 1 MOA at 25 yards) = 6 MOA

• I need 6 MOA in adjustments to correct, and since I’m shooting too low, I need to come up.

• Next, 6 MOA / 0.5 MOA (the EXPS3 has 0.5 MOA adjustments) = 12 clicks.

• It’s going to take me 12 clicks UP using the elevation turret to make my POI the same as my POA.

• Let’s make the adjustments and see…

3. Shoot Another Group to Confirm

Example continued... Perfect!

3 VS 5 VS 10-shot groups? Aim for the center again and fire a round to confirm. Though one-shot zeros are done, it’s advised to shoot groups for a better picture of good loads, accurate rifles, and one’s skill level.

At any rate, though 3-shot groups may suffice, 5-shot groups are deemed the standard while 10-shot groups are considered even better.

4. Repeat the Process

Repeat this process if you don’t quite get close enough to the POA to determine zero. Minor tweaks and adjustments may be all that is needed. Repeat again as necessary if you’re zeroing for a longer distance.

• What is the best zero distance for a pistol?

Handguns with optics are typically sighted in at 15, 20, or 25 yards.

• What is the best zero distance for a rifle?

Rifles with red dot sights are usually zeroed for 25, 36, 50, or 100 yards.

Which Red Dot Sight is Right for You?

Red dot sights are not created equal, and they each have highlight features that lend them better to certain applications than others – no one RDS does it all. Considerations like battery runtime, dot size, and specialty features will have a role to play in which is best for you.

Below are reflex sight recommendations for the AR-15 to pistols and shotguns, use with NV or a magnifier, for hunting, CQB, or home defense, and more.

1. AR-15

Our best budget red dot sights (all field-tested!) are all-time, favorite optics to mount to an AR-15, so say the masses. Going with a high value RDS, the Holosun HS403B with Shake Awake, NV compatibility, and a 50,000-hour battery life wins out first place. The downside? The tedious battery tray – it’s a great design but the tiny screws are so, well, tiny!

If you place a lot of value in an included quick detach mount, the STNGR Axiom II has my every recommendation. My favorite key features include its crisp dot, 50,000-hour battery runtime, and its intuitive, easy-to-use illumination knob. For its simplicity, I’m pulling rank on this one.

2. Pistol

There are many pistol sized red dot sights that can be considered, but one of the most proven miniature sights to name is the Trijicon RMR Type 2. It’s a go-to when one wants quality, performance, and reliability in one package for hunting to professional applications. The RMR has a 6.5 MOA dot, auto and manual brightness, and a battery life that can keep on giving for over 4 years.

3. Shotgun

The Aimpoint Micro S-1 is deliberately designed for use with shotguns. It has a 6 MOA dot for fast reticle-on-target acquisition and following moving targets, i.e., birds.

Of note, the S-1 has an interchangeable base but has an ideal, ultra-low profile for an optical axis closer to the bore. It’s more than tough enough to handle the wet conditions of waterfowl hunting, is highly visible with extra brightness, and will last several seasons with a continuous-on 50,000-hour battery runtime.

The drawback? Definitely the high price.

4. Night Vision

Without doubt, the best sights for use with night vision would be an EOTech holographic sight. The “3” line of the XPS and EXPS series offer up 10 night vision-compatible settings which is much more than any reflex sight can compete with.

Additionally, the huge window may help with seeing and alignment especially if you’re running helmet-mounted NODS. In particular, the EXPS3-0 has proven to be a sight that can handle anything. By the way, it’s Target Tamers field-tested!

5. Magnifier

Hands down one of the best red dot sight and magnifier combos in the market is the field-tested pair, the Sig Sauer Romeo MSR & Juliet Micro 3x bundle set.

They’re perfectly matched to mate together for a fast transition between non-magnified and 3x magnification for target identification/observation and shooting. They’re also one of the most affordable combos without compromise on quality – this equates to inherent value!

6. Hunting

You don’t need all the bells and whistles for a hunting RDS. What you want is dependable performance, a crisp dot, dim enough illumination to use in lowlight conditions, and a price that doesn’t break the bank. The first RDS that comes to mind that meets the criteria? The Vortex Crossfire II. It also works great with a magnifier – and that may come in handy in a hunt. We know because we tested it!

7. Home Defense

A lot of people like to have motion sensor activation on their home defense and SHTF red dots for their AR-15. If you’re one of them, you’re limited to a few manufacturers in the industry, which could mean a higher price… right? Not always.

The Sig Sauer Romeo 5 is an exception because it falls into the budget red dot sights price range. It’s complete with MOTAC that automatically deactivates the dot after two minutes – tested and it works. With its fast deactivation time, battery life is conserved. For this reason, it’s ideal on a home defense rifle that is tucked safely away but ready to help you put self-defense into your own hands.

8. Law Enforcement

Aimpoint, Trijicon, and EOTech are well-known manufacturers among LEA. The preference for either one may largely depend on the budget regardless of a LEO’s personal favorite.

Even so, there’s no reckoning that the Aimpoint Pro Patrol RDS is a well-known front runner. Perfect for the duty AR-15, it’s patrol-optic ready with continuous-on illumination, a 2 MOA dot, is NV-compatible, and has a transparent rear cap.

9. CQB

CQB is what red dots and holographic sights do best. To further slim the judging parameters for this subsection, let’s peek at LE records. LEOKA reports that a high percentage of feloniously killed LE professionals occur in incredibly close ranges – mere feet. Both LEOKA 2010-2019 stats and Use of Force End of Year Reviews by agency may also show that handguns are used in OIS incidents more than any other type of firearm, respectively, rifles and shotguns.

With an unexpected engagement in mind, a carry handgun is the closest firearm instantly ready for CQB use as it’s more than likely always present on your person.

The sight recommended for CQB is the Holosun EPS Carry Red 6 red dot sight. It has a 6 MOA dot for high visibility which will prove helpful in adrenaline-surging engagements. Key features include Shake Awake, a 50,000-hour battery life, and an ultra-low deck height for use with standard-height irons.

10. Long Range

As previously discussed, a single red dot can be used as the aiming point for two very different distances, i.e., the 50/200-yard zero. However, running ballistics, using the right loads, and your effectiveness will determine accuracy. The EOTech XPS2-2 gives you four aiming points.

It has two 1 MOA aiming dots surrounded by a 68 MOA ring. Using the center dot for a 50/200-yard zero, the second dot would be for 500 yards and the base of the ring would be for 7 yards. This is calibrated for .223 cal. 62 gr. 2,900 vel. loads. If you’re using something else, you’ll need to run ballistics and verify what the distances are for you.

11. Battery-free Operation

There really isn’t a “battery-free” RDS but there are sights with an integrated solar panel that can provide illumination if a battery fails. It’s said that the illumination isn’t as bright via solar energy versus a battery, but it counts for something especially if you’re not running iron sights.

A highly praised, favorite, field-tested RDS that is known for its dual power source is the Holosun HS510C. In auto mode, solar energy, the illumination is set to automatically adjust for the conditions. In manual mode, you have 11 brightness settings that includes two that are NV-compatible. It also has Shake Awake, a quick detach mount, and a 2 MOA dot and 65 MOA ring reticle. Since Holosun tends to go “all-out,” you can switch up the reticles too!

Don’t Overthink It!

Seeing all this information on one page is no doubt overwhelming. Remember that this is an all-inclusive guide, and some of it may not apply to you.

The basics are covered: how to use an RDS, how to zero it, and which ones are best for various applications based on their respective, key features.

As you become familiar with using a red dot, zeroing it in, and seeing how easy it is to use, you may find yourself adding accessories to complement your setup down the road like a magnifier. This may happen sooner than you think!

Take your time and don’t overthink it. The gist is, point and shoot. Be safe and have fun!

Further Reading

• Monstrum Marksman 3x30 (P330-B) Review – RANGE-TESTED!
• Monstrum Blackbird 3x30 Prism Scope Review – Range Tested!
• Swampfox Raider 1x20 Micro Prism Field Test – RANGE-TESTED!
• How Accurate are Red Dot Sights?
• 2 MOA VS 6 MOA - Which Dot Size is Best for You?