Meprolight M21 Review

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Hey Shooter! Welcome to Meprolight M21 Review.

I’ve had the pleasure of putting the Meprolight M21 through its paces. This reflex sight, renowned in shooting circles, stands out for its reliability and efficiency. 

My hands-on experience with the Mepro M21 has given me a comprehensive understanding of its performance, which I’m excited to share with fellow enthusiasts.

Overview of the Meprolight M21

The Meprolight M21 isn’t just another red-dot sight; it’s a testament to innovative optical engineering. This reflex sight, well-regarded among shooting professionals, brings a new level of precision to the field. 

Its design is a balance of practicality and advanced technology, tailored for shooters who demand both reliability and uncompromised visibility in various lighting conditions.

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Meprolight M21
Meprolight M21 Self-Powered Day & Night Reflex Sight

Core Specifications of the Meprolight M21

Power SourceFiber optic and Tritium
Lens Diameter30mm (1.1811 in.)
Reticle ColorAmber
Field of ViewUnlimited with both eyes open
Brightness IndexAuto Adjust
Reticles4.3 Bullseye, 4.3 Dot, Triangle, X
Dimensions (LxWxH)4.45 x 2.17 x 2.8 in.

What’s in the Box?

  • Mepro M21 Reflex Sight
  • Quick Release Picatinny Adapter
  • Black Dust Cover
  • Lens Cleaning Cloth
  • Dust Brush
  • User Manual

First Look & Impression

Unboxing the Meprolight M21 was quite an experience. Its sturdy build immediately suggests durability, and the sleek design indicates a well-thought-out sight. Handling the M21, you feel its robustness, an essential trait for any field equipment. 

The clarity of the lens and the distinct amber-colored reticle caught my eye, promising an unobstructed and sharp targeting experience.

Who Should Get Meprolight M21

The Meprolight M21 is an excellent choice for serious shooters. Whether you’re into competitive shooting, hunting, or tactical applications, this sight’s adaptability and consistent performance in various light conditions make it a valuable asset.

Types of Guns Suitable for this Sight

  • AR15 type firearms
  • Kel-Tec KSG
  • UZI semi-auto carbine
  • Rifles with a Picatinny Mount

Top 7 Features of Meprolight M21

1. Dual Illumination System

The Meprolight M21’s standout feature is its dual illumination system, a masterful blend of tritium and fiber-optic technologies. This system ingeniously utilizes ambient light during daylight, providing a bright and clear reticle. In low light or nighttime conditions, the tritium illumination takes over. 

This seamless transition is automatic, ensuring the reticle’s visibility is always optimal. The tritium light source, a self-illuminating system, is particularly noteworthy for its longevity, requiring no external power source. 

This feature is a game-changer for shooters who find themselves in varied lighting environments, as it offers consistency and reliability without the need for battery power.

My Testing

During my testing, the dual illumination system of the Mepro M21 performed exceptionally well. In bright daylight, the reticle was vivid and sharp, aiding in quick target acquisition. As the day transitioned to dusk and then night, I observed the tritium illumination take over smoothly. 

The brightness level at night was impressive, providing clear visibility without being overpowering. This feature proved especially useful during a dusk-to-evening shooting session, where I experienced first-hand the M21’s ability to adapt to changing light conditions without any manual adjustment.

2. Rugged and Reliable Design

Ruggedness and reliability are at the core of the Meprolight M21’s design. Built to withstand extreme weather conditions, the M21 is not just durable but also dependable. 

It’s been rigorously tested and used by military and law enforcement agencies globally, including the Israel Defense Forces. This level of endorsement speaks volumes about its robust construction and operational reliability. 

The sight’s design ensures it can handle the rigors of intense use, whether in training, hunting, or tactical operations.

Its compatibility with night vision goggles and magnifying scopes enhances its versatility, making it suitable for a wide range of applications.

My Testing

Putting the M21’s ruggedness to the test, I exposed it to various environmental conditions, from rain to dusty terrains. Its performance remained unhampered.

The sight maintained its zero after several rounds of recoil, a testament to its solid construction. Using it with night vision goggles showed no noticeable decrease in field-of-view or performance, confirming its compatibility and robustness in varied tactical scenarios.

3. Large Field of View and Reticle Options

The Mepro M21 boasts a large 30mm diameter lens, providing an expansive field of view. This feature is crucial for rapid target acquisition, a key factor in both competitive shooting and tactical scenarios. 

The sight offers five different amber-colored reticle options, including MOA or 5.5 MOA dot, Triangle, 4.3 Bullseye, and X. These options cater to various preferences and shooting requirements, ensuring that users can select the reticle best suited to their specific needs. 

The amber color of the reticle also aids in contrast against different backgrounds, enhancing visibility and precision.

My Testing

During my time with the Mepro M21, the large field of view significantly eased the task of acquiring targets quickly. The various reticle options allowed me to experiment with different types of shooting. 

I found the 4.3 MOA dot particularly useful for precision shooting, while the Triangle reticle was beneficial for rapid target engagement. 

The amber color provided excellent contrast in diverse lighting and background conditions, facilitating quicker and more accurate shots. This versatility makes the M21 a strong contender for a wide range of shooting disciplines.

4. Maintenance-Free Operation

The Mepro M21 is engineered for simplicity and reliability, embodying a maintenance-free operational design. The absence of batteries and switches is a significant advantage. 

This design eliminates common concerns about battery life or the need for external power sources. The always-on, ready-to-use status of the sight ensures that users can focus on their shooting without the hassle of checking and replacing batteries. 

This feature is particularly beneficial for those in tactical situations where reliability and quick readiness are paramount. The maintenance-free aspect also means fewer moving parts, reducing the likelihood of mechanical failure and making the sight an ideal choice for rugged use.

My Testing

In my testing, the maintenance-free aspect of the Mepro M21 was a standout. Not having to worry about battery levels or switch malfunctions was refreshing. It performed flawlessly across various sessions, reinforcing its reliability. 

This feature added an element of confidence, knowing that the sight would be ready whenever needed without any preliminary checks or preparations.

5. Compatibility with Standard Picatinny Rail

Compatibility with standard Picatinny rail systems is a key feature of the Mepro M21, enhancing its versatility. This compatibility allows the sight to be easily mounted on a wide range of firearms, making it a suitable option for various types of shooters, from sports enthusiasts to tactical professionals.

The quick-release Picatinny adapter included in the package further facilitates easy installation and removal, allowing for quick transitions between different weapons if necessary. 

This feature makes the M21 an adaptable and practical choice for those who use multiple firearms or need to switch their optics between different platforms.

My Testing

During testing, I found the M21’s compatibility with the Picatinny rail incredibly convenient. Mounting the sight was straightforward, and the quick-release mechanism functioned smoothly, allowing for fast attachment and detachment. 

This feature proved particularly useful when I experimented with different firearms, as it offered great flexibility and ease of use.

6. Night Vision Compatibility

The Mepro M21’s compatibility with Night Vision Goggles (NVG) and scopes, including those with GEN III tubes, is a critical feature for tactical and nighttime use.

This compatibility ensures that the sight can be used effectively in low-light or dark environments when paired with night vision devices. The design of the M21 allows for easy positioning of magnifiers close to the sight’s optics, enhancing its functionality with night vision equipment. 

This feature extends the usability of the M21 into varying light conditions, making it a versatile tool for different operational scenarios, especially in military and law enforcement applications.

My Testing

Testing the M21 with Night Vision Goggles revealed its effectiveness in low-light conditions. The sight worked seamlessly with NVG, maintaining a clear field of view and not compromising on the ease of operation. 

This compatibility is a significant advantage for use in darker environments, offering enhanced operational capabilities.

7. Wide Array of Reticle Options

The Mepro M21 offers a diverse selection of reticles, a total of five different types, including MOA or 5.5 MOA dot, Triangle, 4.3 Bullseye, and X. 

This variety caters to different preferences and requirements, allowing shooters to choose a reticle that best fits their specific use case. 

Whether it’s for rapid target acquisition or precision aiming, there’s a reticle option suitable for the task. The amber color of the reticles ensures good visibility and contrast against various backgrounds and lighting conditions. 

This versatility makes the M21 adaptable to a range of shooting disciplines, from tactical operations to competitive shooting and hunting.

My Testing

Exploring the different reticle options was a key part of my testing. Each reticle type offered its unique advantages. The 4.3 Bullseye was excellent for precision aiming, while the Triangle and Dot reticles were ideal for quicker target acquisition. 

The ability to switch between these reticles allowed me to adapt the sight to different shooting scenarios, enhancing its overall utility and performance.

Footprint and Mounting Considerations

The Meprolight M21 showcases a compact and efficient design. It fits seamlessly onto standard Picatinny rails, thanks to its quick-release adapter, making the mounting process simple and hassle-free. 

The sight’s dimensions (4.45 x 2.17 x 2.8 inches) and weight (13.12 oz) ensure it doesn’t add significant bulk or heft to the firearm. This compactness is particularly advantageous for users seeking a balance between functionality and maintaining a lightweight setup. 

The easy-to-mount nature, combined with its sleek profile, makes it an appealing choice for various firearms.

Pros and Cons


  • Maintenance-Free Operation: No need for batteries or switches, ensuring constant readiness.
  • Dual Illumination System: Utilizes both ambient light and tritium, providing clear reticle visibility in all light conditions.
  • Versatile Reticle Options: Offers five different amber-colored reticles, catering to various shooting preferences.
  • Night Vision Compatibility: Suitable for use with Night Vision Goggles and scopes, including GEN III tubes.
  • Rugged and Reliable: Performs well in extreme weather conditions and is used by military and law enforcement agencies globally.
  • Large Lens Diameter: 30mm lens aids in rapid target acquisition and enhances accuracy.
  • Picatinny Rail Compatibility: Easy mounting with quick-release mechanism.


  • Internal Glow problem: The tritium chamber can cast an orange glow, obstructing the view if the head is moved down.
  • Inconsistent Reticle Visibility: Changes in lighting can cause difficulties in target acquisition due to fluctuations in reticle brightness.
  • Faint Yellow Reticle: The amber reticle can appear too faint in certain lighting conditions, impacting clarity.
  • Random Reflections: Occasional reflections in the display can be distracting during usage.

Final Verdict

As a professional shooter who’s had the privilege of testing the Meprolight M21, I can confidently say that this sight is a true game-changer in the realm of optics. 

The M21 stands out with its impeccable blend of functionality, durability, and versatility. Its ability to adapt to various light conditions without manual intervention is nothing short of impressive, ensuring clear visibility at all times. 

The sight’s maintenance-free design, coupled with its wide range of reticle options, provides a seamless shooting experience. Overall, the Mepro M21 is more than just an optic; it’s a dependable partner for any shooter looking for precision, ease of use, and reliability.


How long will a Mepro M21 last?

A Mepro M21 can be expected to function efficiently for about 9 to 10 years, thanks to its durable tritium vial, with an overall lifespan of around 12 years.

How does a Meprolight M21 work?

The Meprolight M21 works using a combination of tritium and fiber-optic technologies, using ambient light in daylight and a tritium light source in low light or at night, transitioning seamlessly and automatically.

What is the warranty on Tru Dot night sights?

The warranty on Mepro Tru Dot® night sights is 12 years from the date of original retail purchase, ensuring long-term reliability and support.

Does the military use Meprolight?

Yes, Meprolight products, known for their precision, durability, and accuracy, are used and trusted by militaries, law enforcement, and professional shooters worldwide.

Where is Meprolight M21 made?

The Meprolight M21 is made in Israel. It’s a reflex sight that uses dual illumination; fiber optics for ambient light and a tritium lamp in low-light conditions.

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