Holosun 503CU Review – Range Tested Review

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Welcome to Holosun 503CU Review in 2024.

If you have been keeping up with my previous reviews, you probably already know how big of a Holosun fan I am. And rightfully so —what’s not to love about their optics, after all? They are high-quality, very precise, and incredibly durable, all of which make my shooting experience a success overall. 

Today I will be reviewing one of their products from the 503 series, 503CU to be exact.

This Holosun 503CU review covers everything, including details about dot quality, durability, and price range. To help you decide if this sight is right for you, I will also share my personal opinion and experience with this sight. Let’s get right into it.


Housing MaterialAluminum
Item Dimension5 x 4 x 4 inches
Weight4.87 oz
Parallax FreeYes
Unlimited Eye ReliefYes
Reticle ColorRed
Reticle Options2 MOA Dot & 65 MOA Circle
Battery TypeCR2032
Battery Life50000
Night VisionYes
Power SourceSolar & Battery

Compare Deals:

Holosun 503CU
Holosun HS503CU, Paralow Red Dot Sight
Holosun HS503CU Paralow Red Dot Sight 1x 20mm 65 MOA Circle with 2 MOA Dot Picatinny
Holosun HS503CU Multi-Reticle Circle Dot 20mm Micro Reflex Sight
Holosun HS503CU Red Dot Sight
Holosun HS503CU 2 MOA Circle Red Dot Sight

What’s in the box?

Upon opening the box, you will find the following items inside:

  • The Optic Itself
  • Low Profile Mount
  • Lower 1/3 Cowitness Mount
  • Screws
  • Lens Cleaning Cloth
  • CR2032 Battery
  • User Manual
  • Rubber Cover
  • Battery Tray Cover

Features of Holosun 503

The Holosun 503CU is equipped with the best technologies the red dot sight industry has to offer. The 503CU is well-deserving of approval for its characteristics that give practical convenience and field performance. Let’s get right into its features.

1. Reticle

Speaking of a reticle, this sight has a multi-reticle system with a 2 MOA dot and a 65 MOA circle, allowing you to choose between the two depending on your needs. You lose battery life with a 65 MOA outer circle, but I personally like it because you can use it as an auto-ranging feature. Personally, I find it to be a little bit quicker, and up close, you can simply toss the circle on a target and pull the trigger as quickly as you like.

2. Dot Adjustment

Dot adjustment is quite easy on this optic. Simply hold down the minus, and it will cycle between whether you want the dot or the circle dot and if you want to move from one to the other. Additionally, it controls whether you want to run in manual mode or automatic mode. I personally prefer to use my red dots in manual mode. You can pick whatever mode you prefer. Automatic mode will automatically adjust brightness.

Furthermore, it also has an awake shake feature that allows you to set a sleep timer on your optic for 10 minutes, 1 hour, and 12 hours. When you press the + button, one blink means the optic is on sleep for 10 minutes, two blinks mean it’s on sleep for an hour, and three blinks mean it’s on sleep for 12 hours.

Moreover, this sight has 12 brightness settings, 10 of which are daylight brightness settings and two of which are night vision brightness settings.

3. Construction and Durability

The 6061 T6 aluminum used in the Holosun 503CU construction is pretty solid. Even though the material is obviously not as strong as the 7075 Aluminium used in Holosun’s other high-end optics, it still manages to get the job done fairly well. This Holosun optic, like all others, lives up to its reputation for durability and its propensity to develop optics that can endure everything. This sight is also waterproof, so you may shoot in the rain or other adverse conditions without fear of your optic failing.

4. Battery

This sight uses a CR2032 battery and has a battery life of up to 50,000 hours, though that obviously depends on your brightness level. Realistically, I’d say that the battery lasts 20,000 hours on setting 6.

As previously mentioned, it includes an auto-on, auto-off battery that allows it to automatically turn off after a predetermined period of inactivity and turn back on as soon as it detects motion. The auto on and off feature has essentially worked perfectly on every Holosun optic I’ve ever tested, and 503 has been no exception.

Solar Failsafe Technology is also included in the Holosun 503CU. If your battery fails, solar technology provides a backup power source when natural or artificial light is available. It is enabled while in Auto Mode, and the reticle intensity is automatically changed based on the amount of light received by the solar cell. In strong light, the reticle is brighter, and in low light, the reticle steps down in intensity to match the lighting conditions. On models equipped with a supercapacitor, it is possible to run the optic constantly, both during the day and at night, by maintaining a charge via the Solar Failsafe System, all without the use of a battery.

So, if you shoot outside in the sun as I do, you can stay on solar all day, which is a huge benefit.

5. Weight

Surprisingly, 503CU does not weigh as much as you may expect. It weighs around 4.87 oz. It’s fairly light and easy to carry around.

6. Sight Picture

The glass clarity and sight picture on this sight are excellent. Some optics have a lot of color deviation. However, this one does not. When it comes to glass clarity, it is really crisp. The quality of the sight image is nearly as good as seeing through much more expensive options. This sight is designed for shooting at a maximum range of 9mm (around 100 yards).

7. Eye Relief

There’s no need to be worried about eye relief with this optic. You can shoot with both eyes open and get a clear image. This is also beneficial to situational awareness.

8. Mounting

The Holosun 510CU is simple to mount. The Holosun 503CU comes with two mounts. The first one is a low mount. This mount can be used when you have a firearm with a drop to the stock, such as an AK. Most shotguns and almost all rifles, with the exception of the AR platform, have drop stocks. The other mount that comes with the box is a lower 1/3 mount. This mount is commonly used on an AR-15 and allows the use of flip-up or fixed iron sights. This height allows the iron sights to be seen through the optic’s glass.

My Experience with Holosun 503CU

I’d rate this sight a solid 4.5 out of 5. It works nicely for me and does a good job. In my opinion. Although people like the 400 series since the characteristics are pretty similar to 503, the 400 series is a bit basic and only has a 2 MOA dot. The 500 series, however, adds more features, such as a 2 MOA with 65 MOA circle dots, which many people, including myself, prefer. Higher-end lenses such as the Holosun 515 and Holosun 530 series could potentially be considered, but they are more expensive, making the 503CU a reasonable and suitable option while still keeping the features. 

Overall, my experience with the Holosun 503CU has been incredibly great. It’s an excellent choice for anyone looking for a low-cost red dot for a defensive or competition rifle. However, I’m not sure if I’d put this red dot on a law enforcement or army rifle. Yes, I’ve seen this red dot used on a duty rifle with no problems. However, the plastic battery tray could be a problem in that case. If it weren’t for that, I’d say you could use this optic on a duty rifle with confidence. Aside from that, this is a great optic for any civilian carbine, defensive or not. If you’re looking for an affordable yet effective red dot, I strongly advise you to take advantage of such a low-cost option.

See My detailed comparison between Holosun 403 and 503.

Holosun 503CU’s Main Features

  • 20mm Window Size
  • 6061 Aluminum Material
  • 1x Magnification
  • 2 MOA Red Dot with a 65 MOA Circle Dot
  • LED Illumination Type
  • CR2032 Battery Type
  • 50k Hours of Battery Life
  • 0.5 MOA Adjustment
  • 50 MOA Windage
  • 50 MOA Elevation
  • Full Co-Witness Mount, Quick Release Mount Type
  • Water Resistant Up to 1m
  • Unlimited Field of View
  • Parallax Free with Unlimited Eye Relief
  • Reliable Construction
  • -40℃~70℃ Storage Temperature
  • -30℃~60℃ Working Temperature


That brings my Holosun 503CU review to its conclusion. To put it simply, the Holosun 503CU is a high-quality red dot sight from one of the most well-known manufacturers. Holosun has a large list of comparable sights, but the 503CU is a must-try for its range of brightness settings and solar power panel for longer battery life. The Holosun 503CU is an ideal option if you want a red dot sight with an unlimited field of view for your firearm that is also reasonable and budget-friendly.

Frequently Asked Questions

What is the difference between Holosun 503C and 503CU?

The main difference between the Holosun 503C and 503CU is that the U variant has increased turret protection.

How many models does the Holosun 503 Have?

The Holosun 503 comes in five different models: 503BU, 503C, 503CU, 503GU, and 503FL.

Is Holosun 503CU waterproof?

Yes, Holosun 503CU is waterproof. In addition to that, it is also fog proof and shockproof. 

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