Holosun HS403B
  1. Holosun HS403B

Holosun HS403B

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  • Reticle
  • Battery Life
  • Brightness Setting
  • Build Quality
  • Price/Value
4.2/5Overall Score

The Holosun HS403B is a red dot sight by Holosun that features Shake Awake, a technology designed to save your optics battery life and prevent you from putting your gun down and forgetting to turn off your optic. The HS403B is the perfect red dot sight for any AR-15 style rifle.

  • Reticle: 2 MOA Dot (Green and Red Available)
  • Battery Life: Up to 50,000 Hours on Setting 6
  • Brightness Setting: 10 DL & 2 NV Compatible
  • Battery Type: CR2032
  • Parallax Free & Unlimited Eye Relief: Yes
  • Price for Performance
  • Ease of Use
  • Shake Awake™
  • Torx wrench is pot metal at best
  • Battery may be difficult to find in a pinch
  • Made in China

I was in the market for a sub $200 red dot sight for one of my AR-15’s that hardly ever saw use, a trunk gun, if you will. The goal was to get an inexpensive, reliable, and battery effect red dot that would hold a zero. So the Holosun HS403B was one of the top contenders right off the bat.

Finally, I settled on the Holosun HS403B because it seemed reliable, and at $139.99, it met the price point requirements that I was looking for.

HS403B Stock Photo

Holosun HS403B

• 2 MOA Dot Reticle
• 50,000 Hours Battery Life
• 12 Brightness Settings
• Convenient Tray Battery
• Parallax-free

Holosun HS303B First impression

The Holosun HS403B isn’t a standout red dot sight. It looks about like you’d expect any red dot to look. The box the Holosun comes in is a small white box with a picture of the sight and the model number in the top right-hand corner. The bottom left-hand side of the box shows the dot options the optic features.

Most of the Holosun red dot sights look very similar. Once you open the box it has cut closed cell foam protecting the red dot, extra compartment, mount, adjustment tool, and paperwork.

hs403b in the box

After you get done eyeing the box and actually grab the red dot sight. You’ll finally get to feel the red dot. The HS403B is an all-metal build and comes with a few different mounting options. 

After handling the HS403B, my first impression of the optic is positive and it would seem I did well on this purchase. 

Holosun HS403B Materials

HS403B is made of 6061 T6 Aluminum and has a protective rubber cover included in the box. 

The optic coating on the red dot is MAO, which seems to be helping up well and is scratch resistant. While I’m not sure if it’s the same coating, I scratched the 1/3 co-witness mount when trying to get it off.

I had a slight issue with the included Torx wrench where I accidentally mounted the optic on backward, pro-tip don’t be in a hurry! While taking the mount off, I broke the included Torx wrench off in the mounting screw. I was able to get the broken Torx wrench piece out of the screw and easily get the screw out by using a Torx wrench made of real metal, not the non-sense included with the red dot.

HS403B Stock Photo

Holosun HS403B

• 2 MOA Dot Reticle
• 50,000 Hours Battery Life
• 12 Brightness Settings
• Convenient Tray Battery
• Parallax-free


HS403B’s listed weight is 2.82 oz and throwing it on the scale with the mount attached comes in at 4.3 oz.

This is good compared to sights like the Sig Romeo 5 at 5.1 oz and lighter than the Primary Arms SLx MD-25 which clocks in at 6.5 oz.

A fair weight for a red dot sight, not too heavy, not write home and tell yo’ momma lite.

At this price point, I don’t think you can really complain about the weight, but even if you are that picky you won’t complain about this red dot sight’s weight.


The reticle on the Holosun HS403B is a single 2 MOA red dot. The optic features 1x magnification is parallax-free and has unlimited eye relief. The dot is clear and crisp depending on what setting you have the dot on. If you have the dot maxed out on setting 12 you’ll notice it’s not a small crisp dot anymore. You’ll get a red circle around the glass that is a bit rough.

However, running this red dot on setting 3-11 it’s a nice crisp dot, you won’t be disappointed with the 2 MOA dot.

Furthermore, the reticle is available in both red and green dots, so if you prefer a green dot that is an option as well.

Holosun HS403B Dot Adjustment

Adjustment of the dot is simple with a turret style adjustment on top for elevation adjustment.

The side adjustment knob is a horizontal adjustment, and both are slotted screw designs. You will need to use a small screwdriver or tool to make your sight adjustments.

Holosun HS403B Adjustment Knob

The turret adjustments are protected by a small-cap that you can screw on and off by hand.

The dot on the HS403B red dot sight has 12 brightness settings. 10 for daylight operation and 2 are night-vision compatible.

Power source

The power on the sight is powered by a single CR2032 battery and is loaded into a small tray.

The HS403B comes with an extra tray and slides directly into the side of the optic. I must say I’m not a huge fan of the way this battery goes into the optic. The tray can be somewhat finicky, and I had a time with the tray. Make sure you have the CR2032 battery positive side down, or you’ll spend a good bit of time figuring out why your optic isn’t working.

Included in the box are two battery trays, but I can’t figure out why. This isn’t a con to the HS403B; I just can’t figure out for the life of me why I need two trays. It makes me wonder if the trays are prone to breaking.

The tray does have an o-ring around the end where the screws are, and it’s where the tray meets the optic housing. This creates a seal, and per the instructions, if you don’t secure it well with the screws, water or other debris could get into the red dot sight and damage it.

The only issue with the o-ring style design is that you don’t know exactly what’s “over tightened” or “just right” and sealed off. You’ll need to secure your screws and hope your feeling of just right is good enough to keep water out.

HS403B Stock Photo

Holosun HS403B

• 2 MOA Dot Reticle
• 50,000 Hours Battery Life
• 12 Brightness Settings
• Convenient Tray Battery
• Parallax-free

Holosun HS403B Durability

First, let me address durability as it’s gonna be a hard line item to judge unless you really put an optic to the test. It’s not that I wouldn’t put any optic I have through the wringer for the sake of testing a tool to its limits.

The reality of it is there would have to be a standard of durability testing established before determining an optics’ true durability. Because of that, I’ll give this disclaimer on my durability comments:

Durability Disclaimer: Until I come up with a standard set of durability tests for each optic, I will only summarize what the durability claims are by the company and what they appear to be at the time of this writing based on my use of the optic.

The optic itself feels up-to-par in terms of durability and toughness. I really like the fact it’s an all-metal housing is T6 aluminum.

Sight Picture

To preface the sight picture section, I shoot with both eyes open, as you are supposed to. I’m giving my opinion on the sight picture based on how I use the optic.

hs403b sightpicture 1

The overall sight picture isn’t bad. If you are used to something like the Aimpoint T-1 or Aimpoint T-2 this will be similar. The picture is good and the red dot is crisp.

Mounts and Mounting Options

The Holosun HS403B comes with two mounting options in the box. The lower 1/3 Co-witness Mount and a low profile mount.

I’d use the low profile mount on this for something like a pistol caliber carbine like the CZ Scorpion EVO 3 S1, Sig Sauer MPX Copperhead, or the PSA AKV.

The 1/3 co-witness mount is perfect for your AR-15 rifle, it fits perfectly on my Ballistic Advantage AR-15. It clears backup sights, flashlights, tape switches, and any other rail-mounted accessories.

hs403b rightside
1/3 co-witness mount

You can get a different mount that fits your liking if you find the included mounts to be subpar.

Holosun HS403B the best red dot?

Is the Holosun HS403B the best red dot? Hard to say. Is the HS403B the best Holosun optic for your AR-15? Maybe.

It really boils down to two things here. Does the feature set lineup to your needs and is the price point right?

I really like the shake-awake feature that the HS403B gives you and the battery life is impressive.

Overall, I would recommend this optic to anyone looking for a responsibly priced optic that performs well. If the HS403B is higher than your budget, check out our Bushnell TRS-25 Review. On the flip side, if you want to spend a little more, you can pick up the Primary Arms SLx MD-25 ACSS.

HS403B Stock Photo

Holosun HS403B

• 2 MOA Dot Reticle
• 50,000 Hours Battery Life
• 12 Brightness Settings
• Convenient Tray Battery
• Parallax-free
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Michael Savage
Michael Savage

Michael is the President of Lynx Defense and an avid gun owner and outdoors man. He's passionate about helping find the best bang for your buck and helping others learn about firearms and the industry as a whole.

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