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Holosun Paralow HS503G ACSS

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Holosun Paralow HS503G ACSS Details

About the Paralow series

Paralow is one of the red dot sight series made by Holosun. On the outside, these small tube sights are very familiar to the Micro red dot sights made by the famous Swedish red dot sight manufacturing company. The illumination is powered by a CR2032 battery. The click value for the elevation and windage adjustments is 0.5 MOA. These durable red dot sights feature a single-piece housing made out of aluminum. Altogether, there are 12 illumination intensity levels to choose from, 2 of which are NVD compatible. The battery life is 50.000 hours.

About the model family

The 503 is one of the model families in the Paralow series. Normally, the first number '5' in its name suggests that the user can switch between a 2 MOA dot and a 2 MOA dot surrounded by a 65 MOA circle. This model, however, is a little bit different – the user can switch between a 2 MOA dot and an ACSS reticle. The second number '0' implies that the product comes with standard accessories (without honeycomb filter, quick-release mount and flip-up lens covers).

About the product (HS 503 G-ACSS)

Holosun 503 G ACSS is a red dot sight of the Paralow series

The letter 'G' means that the battery compartment of the red dot sight is on the right side of the device, under a round-shaped cover. Also, it lacks the solar panel, which is why this model has buttons for the regulation of illumination intensity on the top instead of on the side.

Holosun Paralow HS503G red dot sight is of the small tube type and thus bigger than a typical open reflex sight.

This model comes with Primary Arms' ACSS reticle which is popular because of its all-round use (it allows ranging, features BDC dots and wind leads, etc.) It is compatible with many calibers, including 7.62 NATO and 5.56 NATO (holdovers from 100 yards to 600 yards).

Holosun ACSS 503G features the ShakeAwake function. When left powered on, the device will go from 'active mode' to 'sleep mode' after a while to prevent unnecessary battery drain. Once moved, it will power back on immediately.

Holosun 503G works perfectly with a 3x magnifier which makes it easier to clearly see the bullet drop compensation reticle.

Main features:

  • 2 MOA dot & ACSS CQB reticle

  • comes with a low mount and a high mount for lower third co-witness on standard AR platforms

  • ShakeAwake

  • same mounting platform as Aimpoint Micro devices

  • 12 illumination intensity levels, 2 of them are NVD compatible

  • Parallax free

  • 50.000 hours of battery life

  • the battery compartment is on the right side of the device under a round shaped cover

  • this red dot is not solar powered

Mounting details

These small tube sights come with a high mount for an AR platform (lower 1/3 co-witness) and a low mount for other mounting purposes (such as mounting on a rifle). All models in the Paralow series except the ones with the letter 'A' in their name have the same mounting platform as the Aimpoint Micro devices.


Holosun red dot sights (non-elite models) come with a 5-year warranty on the material and 3-year warranty on the electronics.

For more information regarding the Holosun symbols, check our blog post.

Holosun Paralow HS503G ACSS Specifications

Dot sight seriesHolosun Paralow
Made inChina
In production since2017
WarrantyHolosun Classic - 5 years (Housing) / 3 years (Electronics)
Click Value No
Windage - mrad. 0mrad
Windage - MOA.0MOA
Reticle position No
Reticle illumination Yes
Illumination color Red
Usable at daytime Yes
Automatic Turn Off No
Size of Dot.0MOA
Adju. intensityNo
Intensity controlNo
Parallax setting Free of Parallax
Length.0 mm
Width.0 mm
Height.0 mm
Working temperature range-
Power Supply UnitCR2032
Battery lifespan.0h
Filled with -
Lens coatings Fully Multicoated
Tube size/diameter -
FootprintAimpoint Micro standard
Mounting StandardNo
Mount type - IntegratedFixed mount
Mount length.0mm
Size of windowNo
Dot Sight TypeSmall tube sight
Water proof Yes
Fogproof Yes
Shock proofYes
Type of mount rail Picatinny Mount


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Reviews & Testimonials

Reviews for Holosun Paralow HS503G ACSS

3 reviews
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Holosun Paralow HS503G ACSS By
Holosun Paralow HS503G ACSS is a Great Red Dot optic for the money, or for any money, light and sturdy, comes with all the acessories needed to mount it on a rifle/ shotgun. The ACSS reticle is great for several calibers. It is a shame it is not available anymore. Holosun and the ACSS reticle are a great combo.
Would recommend it!!

(Posted on 09/01/2022)

Good optics. By
Glass clarity is good(9/10 compared to Aimpoint)-no distortion, negligible parallax shift, good low light visibility, only a small reddish tint .
Reticle is sharp, with good brightness settings. Chevron is rather small so basically it is usable like a red arrow pointing from below at the point of impact, very easy to utilize. Trough a 3x magnifier dough it is very usable.
windage and elevation adjustment knobs with audible clicks work well. Battery compartment seem pretty watertight-does not come with a battery so have one at hand.
Brightness buttons are on top and that is a bit cumbersome, especially on a heavier rifle, as it implies to hold the rifle shouldered with only the shooting hand while pressing down on the adjustments with the off hand(and the buttons are a bit stiff in order not to be pressed accidentally).
About mounting: The mounts are well made but the high one is very high(on my HK MR223-height of the aperture is 34-35mm from the rail) it co-wittiness at the lower edge of the glass-way lower than 1/3). So I solved the problem like this: for 1/3 co-witness I bought a MNT-RS08S2 riser(20mm rise) in conjunction with the lower mount; for near perfect absolute co-witness I utilize the MNT-RSQD403 riser(15mm rise) with the low mount.
About the seller: good and very fast communication(on technical aspects-asked for some specific dimensions so that I can order the riser before having the optics in my hand and the answer was quick and precise), good packaging, good and fast shipping options,.

(Posted on 02/04/2019)

Good red dot for the price, with an excellent reticle. By
Had this Holosun now for a year. It has been to the range with my roughly thirty times or so and had thousands of rounds fired with it. I have not had a single issue with the optic.

I had to change the battery nine months in, but it has been on quite often (I even forgot it on a couple of times for weeks).

All in all I have been happy with the purchase and can easily recommend this optic. Special thanks go to the excellent ACSS reticle, which works perfectly with an 3x magnifier.

(Posted on 28/12/2018)

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