The HS403A red dot sight gets its day in the sun.

When I purchased my AR-556 earlier this year I knew that I wanted to mount a red dot sight on it. While I didn’t want to break the bank I also didn’t want to purchase something that wasn’t reliable. I was fortunate enough to discover the Holosun HS403A.

The company that produces it prides itself on being high quality and budget-minded; which is great in my book. When I first unboxed it it seemed too small, there’s a good reason for that. The HS403A has a battery compartment that is hidden away in the base of the unit. Also, there is no power switch. This keeps the size of this red dot sight to a minimum. It turns on automatically when it’s moved; so after you load a magazine into the weapon and drop the bolt into battery it’s already on. If you aren’t moving enough to operate the motion switch simply press one of the brightness intensity buttons and it will turn on. The sight boasts 50,000 hours of battery life on setting 5, this is attributed to both the LED technology used as well as the motion activation and auto-off feature. If you forget to turn it off it will do so automatically after eight hours, which sounds like a long time until you consider that it’s only powering an LED. If 8 hours is too long for you you can turn it off by pressing both of the brightness intensity buttons at the same time, you power miser, you.


The HS403A comes with two mounts for your 1913 picatinny rail, a flush mount and a ⅓ co-witness mount. Since I had a rear flip-up sight and the standard A2 front sight, I went with the ⅓ co-witness mount. I had no problems with my sight picture with the added height of the taller mount. When I decided to deploy the rear sight, it performed the way I needed it to; no qualms there. The Holosun sight zeroed quickly with the windage and elevation adjustment covers pulling double duty as the adjustment tools. Simply unscrew them and turn them over to use them as the adjustment knobs. The underside of the covers has the indications for up, down, left and right so you know which way to turn your clicks. I found that it saved time as I didn’t have to look for a coin or a key or a tool, such as my P38, to adjust the zero. It’s aluminum body and mounts keep it lightweight and the PEO/MAO, black finish is said to be more durable than a type III hard anodized finish.


The reticle is a 2 MOA red dot and doesn’t have any other options like a circle or a crosshair. What is selectable is the brightness of that red dot. According to the manual it has 12 levels of brightness; 10 of those settings being suitable for daylight and 2 for night vision. I found the higher end of the selection to be so bright that the dot began to become distorted with a star-burst glare. I tend to run it at setting 7 so that it’s a more cleary defined dot and doesn’t obscure the target with glare. It’s still very visible in the bright Texas sun, so seeing the point that I’m aiming at through the sight has never been an issue. The multi-coated lenses offer no magnification, which hasn’t been a problem for the 100 yd. shots I’ve made with it. It has unlimited eye relief so keeping your nose on the charging handle shouldn’t be an issue. The lenses do appear to have a slightly green hue but I haven’t had any concerns over light transmission. Even in the failing light of dusk I was still able to clearly see, and hit, a 12 inch, white, AR500 steel plate at 100 yds. What can I say; sometimes you just don’t want to pack up when you’re putting rounds on target.


So far I estimate that I’ve put about 500 rounds down range while using this sight with no problems regarding the loss of zero. I’ve removed it and replaced it with ease and re-zeroed it only after I removed and replaced it, as a precaution. It’s seen light rain, dust, and heat with no visible corrosion or wear. So, what’s my opinion of the Holosun HS403A red dot sight? It was what I was looking for and performs well without having to baby it. I believe that it’s a good purchase for what I’m using it for and I’m going to rely on it as my primary sight on my AR. I may deploy the open sights on occasion, just to make sure that I keep in practice. Honestly though, with this sight doing well at 100 yds. I don’t feel the need to practice with my open sights. The fast target acquisition and accuracy that it affords me make this a useful tool on my AR.


Editor’s Note: This Item was purchased by Izzy for his personal use. The review is based on his experience, and opinions and nothing more. If you’d like to see more opinions on it, or order one for yourself, you can get it for a decent price on


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