Review: Holosun 403GL

This is the first in a series of reviews of red-dot scopes for Bullseye.

Headline pictures from


  • The mounting system is interchangeable with the Aimpoint.
  • Screwdriver slot for adjusting windage and elevation.
  • Excellent anti-reflective coating on back glass.
  • No magnification or distortion and almost no dimming of the image.


  • Sight adjustment ‘clicks’ could be better defined.


This is a well made scope that is very similar to the Aimpoint Micro. My preliminary opinion is that it is suitable for precision pistol provided the durability lives up to the rest of the build quality. I am not planning to use it only because the dot is smaller than I prefer.

Image Quality


The anti-reflective coatings are excellent, a little better than Aimpoint to my eyes and much better than Ultra-Dots, Konus or Barska. Reflections are very dim and have a dark green tint. I tried my best to capture reflections in the images below.

Reflections L to R Holosun, Aimpoint, Konus, Match-Dot


The internal electronics are just barely visible at the lower-right of the ring, in the same location, but less visible than in the Aimpoint. See the images below from left to right Holosun, Aimpoint, Konus, Match-Dot.

Sight Pictures L to R Holosun, Aimpoint, Konus, Match-Dot

Magnification / Distortion

Holosun DIstortion

Holosun Distortion Test

There is no magnification or distortion of the image.



There is almost no shading or darkening of the image through the scope, similar to Ultra-Dots (without polarizer), less than Aimpoint and considerably less than Konus or Barska. The filtering looks darker in the picture than it does to my eyes.

Dot Quality


The sight has 11 brightness settings. The first 3-4 are intended for Night Vision (NV) goggles. The first visible setting is 4. Settings 5 & 6 are pretty dim and would only be useful in dim indoor ranges. The remaining settings are fairly linear in steps, except for a large jump between 10 and 11. The max brightness is slightly less bright than the max Aimpoint setting.

I found the jump between settings to be a little bigger than I wanted when shooting indoors at a well lit range with flood lights on the targets and fluorescent lights over the firing position. I would have liked something in-between. The very small dot size required a brighter setting to stand out and be visible against the white paper. The very small point of light is kind of dazzling to my eyes.

Brightness Control

There are two buttons on top of the scope to increase (+) or decrease (-) brightness. The scope remembers the last setting when it powers up again.


The dot shape is very good, round with crisp edges. I don’t see any distortions or flare in the dot. It is similar to Aimpoint, better than many Ultra-Dots, definitely better than Konus or Barska.


The dot size is 2MOA, but looks smaller than the dot on the Aimpoint. It is definitely smaller than I like. I use a 4 MOA dot when using the Match-Dot.

On/Off Control

Pushing any button turns the scope on. Pressing both the + and – buttons at the same time turns the scope off immediately. The scope has automatic shutoff. The default auto-shutoff is 8 hours, but the delay can be adjusted from 1 to 12 hours in one hour increments.

I decided to try the Holosun because the auto-shutoff delay is long enough that I won’t have to worry about it during a bullseye match.

Sight Adjustments

I was disappointed in the group size shooting my old Hammerli 208 International with Aguilla Pistol Match. I was only shooting at 50 feet and expected better. I may take the time to repeat the test using a better gun/ammo combination and/or print some targets with a cross to make aiming easier and more repeatable.


Sight adjustment linearity looks very good. I shot a “sight box” of +/-20 clicks in the image at right. The shots move the same distance regardless of direction. Windage and elevation adjust the POI (point of impact) the same amount.

Elevation / Windage Independence

I don’t see any significant interaction between elevation and windage adjustments. If this was present the box would lean or not be square.

Click Quality

The feel of the ‘click’ is OK, but not great. It feels a little bit mushy and not as clear as an Aimpoint, better than some of my Ultra-Dots, not as good as good as others. At the range I had to concentrate on feeling the clicks as I made adjustments. I don’t think I missed any clicks, like I did testing the Barska.

End Stops

The stop at the CCW end of travel is solid, like tightening a bolt against a metal face. The stop at the CW end of travel is soft, like tightening a bolt against a soft gasket that gets harder the further you go, but never hits a solid stop. If you count clicks, use the CCW end stop.


The sight adjustment is claimed to be 0.5 MOA per click. My testing measured almost exactly 4″ across 40 clicks or 0.1″ per click at 50 feet, which is 0.57 MOA. There are 40 clicks per revolution.

Range of Travel

My example had 372 clicks of elevation and 358 clicks of windage total from end to end.

Sight Adjustment Tool & Caps

Holosun and Aimpoint Cap Markings

Holosun (Left) and Aimpoint (Right)

Holosun Adjustment PedestalsSight adjusters have a screwdriver slot, unlike the two-prong tool needed to adjust the Aimpoint Micro. The Caps have a perfectly matching tab molded in. Sight change directions are printed on the inside of the cap similar to the Aimpoint. The printing looks the same and the arrows are so small that it is hard to see which direction they are pointing, just like the Aimpoint caps. Note that the picture shows more difference between the Holosun (Left) and the Aimpoint (Right) than I can see with my eyes.


Holosun says the scope is water resistant to 1 m. The o-rings around the battery cover and sight adjustment pedestals appear to be good quality, similar to the Aimpoint.


Holosun and Aimpoint Mounts

Holosun (Left) and Aimpoint (Right)

The mounting base is identical to and interchangeable with the Aimpoint. The bottom of the scope housing has 4 mounting screws and a tapered recoil lug. See the picture at right for an image of the Holosun (Right) and Aimpoint (Left). They are identical except for the head of the screws that hold the mount to the scope are Torx on the Holosun and hex (Allen) on the Aimpoint. The threads, length and all critical dimensions are the same.

Sun Shades

Holosun and Aimpoint Side by Side

Holosun (Left) and Aimpoint (Right)

There are no built in sun shades. The front and back glass is barely recessed from the housing, identical to the Aimpoint. The round protrusions at the front and rear of the housing are the same size as the Aimpoint so aftermarket, press-fit, sun shade tubes should fit the Holosun as well.

Disclosure & Attribution

All scopes mentioned in this post were purchased by the author. The Holosun, Konus and Barska scopes were purchased from in August 2016. Aimpoint and Ultra-Dot scopes were purchased from various sources between 2001 and about 2010.

The headline pictures at the top of the page are from All other pictures taken by the author.



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