How To Use A Red Dot Scope

how to use a red dot sight

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Many shooters will say, “A red dot sight is NOT a scope”! Please bear with me. Almost any optical device with an illuminated aiming dot or reticle can fall under the category of “red dot sights.” It includes some magnified red dot optics, which are telescopic magnifying devices. Regardless of the type of red dot sight you mount on your rifle, knowledge of the product and how to use it is essential for safe, accurate, and effective shot placement.

Red dot sights are effective at very close ranges and can be used for close quarters defense as well as more distant targets with both eyes open. Red dots are effective in low light situations.

Years of experience, testing, and research have taught me a few lessons about this class of optics. Read on while we take a look at using a red dot along with the following:

  • Different types of red dots
  • How does a red dot sight work?
  • The pros and cons of red dot sights
  • How to mount and zero a red dot sight
  • Tips for using red dot sights
  • Some of our favorite picks

Different Types of Red Dot Sights

As mentioned, the generic term “red dot” takes in many sights, but the big three are reflex sights, holographic sights, and prism battery operated sights. Here is a quick look at how they work and the pros and cons of each.

Reflex Red Dot

how to use a reflex sight

The reflex red dot is a reflector sight that works by projecting a beam from an led onto a reflective lens seen by the shooter. Reflex sights come in two flavors; the tube type looks like a short rifle scope with the led beam within the housing, and the smaller (sometimes tiny) open reflex optic with an exposed led beam.

Open reflex sight dots are in sharp focus at the plane of the optic. Shifting eye focus to a distant target reduces the focus of the dot and can be problematic for shooters with astigmatism, causing a “starburst, smear, or double vision” dot image. With very low parallax, head movement results in minimal point of aim shift.

Pros

  • Low or no parallax
  • Very long battery life up to 10k hours
  • Smallest and lightest of sights
  • Fast target acquisition with a wide field of vision on open types
  • Unlimited eye relief
  • Cons

  • No magnification
  • Less expensive models may have durability and holding zero issues
  • Astigmatism may cause dot distortion
  • The smallest dots are 2 MOA (increased with flip-up magnifiers)
  • Reflective lens reduces target brightness
  • Holographic Red Dot

    how to use red dot sight

    The holographic red dot uses a laser and mirrors to superimpose the red dot reticle image at a distance on the field of view. The hologram of the reticle is built into the window and is illuminated by a laser diode. 

    The reticle image is always in focus to the shooter regardless of the eye focal point. It appears to be on the same focal plane as the target. The lens and housing serve to align the shooter’s eye with the projector and contain the mechanism.

    Pros

  • Unlimited eye relief with low or no parallax
  • Dot reticle in focus at all times
  • Clearer lens with low brightness reduction
  • Best for shooters with astigmatism
  • 1 MOA dot that does not increase with flip-up magnifiers
  • Cons

  • No magnification
  • Lower battery life 500 -1000 hours (but getting better)
  • Heavier compared to reflex red dots
  • More expensive than reflex red dot sights
  • Prism Red Dot Sights

    how to shoot with a red dot sight

    As the name suggests, prism sights (red dot scopes) use prisms instead of objective and ocular lenses to bring the target image into focus. This reduces the length and weight of the optic over a traditional scope. An led may illuminate a laser-etched reticle such as the one shown below. Some level of magnification is available on some models and usually tops out at 4x to 5x.

    how to use a red dot sight

    Primary Arms ACSS Reticle

    Pros

  • A modest level of magnification
  • The glass-etched reticle is useable even if batteries fail
  • No moving optical parts to fail
  • Reticles include BDC information
  • Better for shooters with astigmatism
  • Smaller and lighter than a traditional scope
  • Cons

  • Magnification tops out at around 5x
  • Susceptible to parallax with limited eye relief
  • Illuminated reticles may wash out in daylight
  • Heavy compared to red dots
  • More expensive than red dot sights starting at about $250
  • How To Mount And Zero A Red Dot Sight

    Mounting

    how to use a red dot scope

    Mounting a red dot is straightforward. Most mount on a standard Picatinny or Weaver rail. I recommend that you mount the red dot sight on the forward half of the receiver rail for AR guns. For me, this is the sweet spot between peripheral vision and the optic field of view. 

    Don’t use a handguard rail. Push the sight forward against the rail and tighten the screws with medium strength Loctite. You should have enough room behind the red dot to mount iron sights or a flip-up magnifier. Adjust quick mounts to firm clamping force.

    Zeroing The Sight

    how to aim a red dot sight

    After mounting the sight, measure the height above bore to the centerline of the sight. The figure below illustrates that the bullet path will arc up to intersect the line-of-sight at the first zero point. The bullet will rise above the line-of-sight to some maximum value and then drop to intersect the line-of-sight at the second zero point.

    Co witnessing a red dot to iron sights is generally not a good way to set windage and elevation. Instead, mount and zero the red dot and then match the iron sights to the optic.

    I am a fan of the 50 yards first zero. Take a look at the ballistic path for the .223 Remington 55 grain PSP bullet. The bullet is only 1.11 inches high at 120 yards and zeroes again at 185 yards with a fifty-yard first zero. This puts you on the money for any target within the reasonable range of a red dot optic.

    Zero your red dot the same way you zero a conventional scope. I zero my ARs at 50 yards, then verify the rise above line-of-sight at 100 yards as per the ballistic calculations. In the case below, the rifle should pattern in at 1 inch high at 100 yards. Pay special attention to the click values on your sight. Most will be either 1 MOA (inch) or ½ MOA (inch) per click at 100 yards.

    how to sight in a red dot scope

    .223 Remington 55 gr PSP - 3240 fps BC: 0.195 zeroed at 50 yards

    RANGE

    VELOCITY

    ENERGY

    PATH

    Yards

    FPS

    FT-LBS

    Inches

    0

    3240

    1282

    -2

    25

    3127

    1194

    -0.89

    50

    3009

    1106

    -0.01

    75

    2894

    1023

    0.63

    100

    2782

    945

    1.01

    125

    2674

    873

    1.11

    150

    2567

    805

    0.9

    175

    2463

    741

    0.36

    200

    2362

    681

    -0.54

    225

    2263

    625

    -1.83

    250

    2159

    569

    -3.67

    Ballistics

    It pays to know the ballistics of all of your guns and ammo combinations.  It’s a sure-fire way to know where your gun is shooting. Go to an online ballistic calculator like shooterscalculator.com to find the dope on your setup. Verify it in the field to be confident in your shot placement.

    Tips For Using Red Dot Sights

    Develop Good Technique

    Practice shooting from all positions with good head position and cheek weld behind the sight. Good positioning should result in a proper sight picture with the red dot appearing in the middle of the window. Speed is fine, but accuracy is final. Shoot slowly and deliberately and call your shots. Even in three-gun competition, speed comes after accuracy is achieved. Practice on different size targets at varying distances to establish your capabilities with the gun.

    Know Your Equipment

    My dear Dad always told me “RTFB” read the full book! Your interpretation may be slightly different. Know the location of power, brightness, and reticle controls without looking. Stalking game in fading light in the rain is not the time to try and figure out your red dot buttons.

    Mounting

    Mount your red dot at a comfortable eye position but not too high. High mounting makes for a loopy trajectory on your ballistic calculations. High mounts also lead to poor cheek weld and shaky shooter’s head positioning.

    Which Red Dot For You?

    Are you looking for a reflex Red Dot for your AR rifle? If so, you can get the best information and top picks right here at HuntingMark.com. View Loyal Brezny’s 12 BEST RED DOTS FOR AR_15 RIFLES.

    Want to know more about Holographic sights and get the low down on the best ones out there? Huntingmark.com has you covered with Megan Kriss’6 BEST HOLOGRAPHIC SIGHTS REVIEWS

    If you want to go the prism Scope route, Huntingmark.com’s Cameron Porter will clue you in with his 8 Best Prism Scopes | 1x to 5x Prism Scopes Reviewed

    Don’t go away yet! This accessory might turn your rifle into the ultimate woods gun.

    Vortex VMX-3T Magnifier with Flip Mount

    using a red dot sight

    One of my favorite woods/hog guns is an AR compact in 300 blackout. A red dot sight was a perfect choice for stalking deer and hogs in the North Texas woods. After reading customer reviews, I decided to order the Vortex 3x magnifier. Adding the Vortex VMX-3T Magnifier with Flip Mount behind the red dot gave me the edge I needed for lengthy shots out to 200 yards. The magnifier has non-critical eye relief.

    The 300 BLK is the ballistic twin of the venerable 30-30 Winchester. As such, it is ideally suited for short to medium-range woods hunting with good practical accuracy. At $199, I wondered if the Vortex 3x magnifier would be worth the price as an add-on. After shooting and hunting with this setup, I’m glad I made the switch from iron sights. I recommend it highly. 

    Vortex VMX-3T

    The price of Vortex VMX-3T varies, so check the latest price at

    Conclusion

    A red dot sight is not the optic for every hunting/shooting need, but they provide a great shooting solution for many short to medium-distance scenarios.  Red dots are quick, versatile, easy-to-use sights. 

    With attachments such as a magnifier, you can increase your effective range without compromising accuracy. Many are capable of use with night vision equipment. You can get into many red dot sights without a big pile of cash and move up to premium gear if it suits your fancy.

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