Test: Red Dot Sight Holosun HS403GL – For a shooting range, not quite for war

Civilian market offers cheaper red dot sights, produced by companies such as Delta Optical, Vortex Optics, and VOMZ, as well as Holosun Technologies, whose Reflex sights (also called reflector sights), which red dot sights are a category of, allow firing without closing one eye. The shooter does not need to restrict his field of vision and retains greater situational awareness. This can be a decisive factor in dynamic competition and real combat.

From the technical side, these are constructions that utilize collimated light—rays of light with little divergence of each other—that is emitted along the axis of aiming. Majority of reflex sights don’t magnify the image. Early reflex sights emitted an opaque beam from laser diode directly toward the shooter’s eye. One eye was used to watch the target while the other focused on the light dot. The first commercial electronic sight using that solution was Aimpoint Electronic created in 1975 by Swedish company Aimpoint. Modern transparent models have the light- -emitting element placed below the targeting line. The light beam is projected onto a special filter or reflecting surface. The shooter sees the target in the lens with a light dot superimposed over it. Electronics development allowed for miniaturization of necessary components. The parts that were bulky, heavy, and hard to fit in the past now became conveniently small and light. It isn’t different in the case of reflex sights. Revolution was lead again by Aimpoint, when in 2007 the company introduced miniature sight Micro T-1. Dozens of articles were written regarding that construction as it became standard to which all the other designs aspire. Now, almost every major producer offers at least one miniature sight model. Aimpoint T-1/T-2 (with even smaller Acro P-1 announced for this year), Vortex Sparc, Bushnell TR25, Trijicon MRO, and SIG Sauer ROMEO5 are some of the popular reflex sight of similar construction. Holosun Technologies alone offers five different models.

Holosun HS403GL reflex sight has a mass of 121 g and dimensions of 66 x 36 x 35 mm. It is powered by a 3 V lithium CR2023 battery which is placed in a socket on the right side of the body

Holosun Technologies is a company founded in 2013 by one of the subcontractors that previously manufactured electronic components for other producers. Company headquarters are located in Walnut, California, but because of cost savings, the fabrication process takes place in China. Holosun Technologies introduced a number of innovative systems to their products, including SolarFailsafe (introduction of solar panel to provide emergency power when the HS403GL is delivered in a box with foam insert, containing the red dot sight on a high mount, an additional low mount, two torx keys, a microfiber cloth, a rubber lens cover, and an instruction manual LED-powering battery discharges), Shake Awake (the sight turns off the light dot when not moved for a preset amount of time, and returns back to preset brightness when moved), Multi Reticle System (allowing change of reticle shape, for example turning off 65 MOA diameter circle, leaving only 2 MOA central dot), and usage of green LED (marked with GR in the model’s name), four times as effective as red according to the producer. The American company has over a dozen small reflex sights in their offer, distinguished by size, purpose, reticle shape, placement of batteries, control buttons, and solar panels. Among them there are models HS403B/C/ GL, HS503BU/C/CU/GU, HS507C, HS508, HS510C, HS512 and HS515CM/CU/GM. After the successes of early sight models, the company also started producing a selection of laser pointers and laser target designators.

Comparison should always be made with the best. That’s why most descriptions and reviews use Aimpoint products as reference. It can’t denied that many aesthetic aspects of American constructions resembles those of the Swedish ones as well. Reflex sight Paralow HS403GL is made of 6061 aluminum alloy, subjected to plasma electrolytic oxidation process which offers better more durable coating than traditional anodizing. The device measures 66 mm in length (2.6 in), 36 mm in width (1.4 in), 35 mm i n h eight (1.38 i n), a nd w eighs 1 21 grams (4.27 ounces). The sight is powered with 3 V lithium battery CR2023, placed within a socket secured with a cap on the right side of the device’s body. The cap unscrews counterclockwise. The battery can be replaced while sight is mounted on a rifle, which is an undeniable advantage. Control buttons are placed on the top of the body. There are two of them, marked with plus (+) and minus (–). The device is powered on by pressing either. Pushing both of them at once turns the device off. The sight has 12 brightness modes, ten for daylight conditions, and two while operating with night vision devices.

Well visible buttons plus (+) and minus (–) at the top of the device. They are used to turning on, off, adjusting brightness, and programming the sleep mode

The red dot sight has twelve brightness levels for the 2 MOA dot shaped reticle: 10 for daylight conditions, and two for night vision operation

The producer declares meeting the PN-EN 60529:2003 protection norms at level IP67. The norm defines levels of protection against solid particles and liquids. The code is composed of “IP” followed by two digits, optionally followed by one or two letters. The first digit measures protection from dust and solid bodies and has range between 0 and 6. The second digit measures protection from water. IP67 represents highest possible level of protection from dust and moderate protection from water. On paper the device should withstand short term submersion, no longer than 30 minutes, up to one meter below surface. In practice the device should withstand strong rain but should avoid longer exposure to streams of water.

Reflex sight Paralow HS403GL is made of 6061 aluminum alloy, subjected to plasma electrolytic oxidation process which offers better more durable coating than traditional anodizing

HS403GL reaches the customer in elegant box with foam insert. Inside you can find the red dot sight itself with a high mount, an additional low mount, two torx keys, a microfiber cloth, a rubber lens cover, and an instruction manual. It would be nice to have a small tube of thread-locking fluid. The set should contain CR2032 battery, which powers HS403GL. Should contain, as it is listed in the manual. The distributor explained its lack from the test set, as restriction on international transportation of batteries, as the battery couldn’t be included with the device itself. Initially, the device was sold in Poland without the battery, which the end user had to buy independently. Since May, the distributor purchases them in bulk and adds to the sets sold.

The set contains two torx keys . Such screw head allows for better transfer of torque while turning . The first key is dedicated to the device’s mount, the second one to clamp that.

HS403GL is delivered in a box with foam insert, containing the red dot sight on a high mount, an additional low mount, two torx keys, a microfiber cloth, a rubber lens cover, and an instruction manual

The first step after pulling HS403GL out of the box was putting in the battery. CR2032 is placed with negative pole toward the device into the sealed battery socket on the right side of the body. Cap thread works with a slight resistance and the socket itself is flat and doesn’t extend much beyond the frame. Indentation on the cap surface can be used to open it with a coin. HS403GL dot brightness has 12 levels of intensity. Ten of them are used for aiming in the daylight, the remaining two are adapted to firing while using night vision devices. The dot at the highest brightness setting is visible in the full sunlight. Change of brightness is achieved by pushing one of two buttons on the top of the device’s body. They are rubbery and work with a noticeable click. Buttons can be easily operated with either hand. It’s a matter of taste if the user prefers such regulation, or traditional knob at the battery cap used by Aimpoint T-1. We haven’t noticed any problems with the buttons, but the knob felt more sturdy and intuitive. The speed is not without the meaning either. Buttons have to be clicked multiple times while Aimpoint’s solution allows for faster brightness regulation.

CR2032 battery socket and the adjustment turrets are flat, not extending far outside of the sight’s outline. Incidental damages to them are unlikely

HS403GL emits a targeting dot with 2 MOA (minutes of arc) of diameter. This means that at the distance of 100 yards (91.44 m) the dot covers 2.1 inch (53.2 mm) of the target. After turning the sight on, time to finally look through it. Surfaces of HS403GL lenses don’t diminish transparency, leaving the image is clear. Some reflex sights have tint that slightly darkness the image, requiring greater focus during firing. The dot itself in Holosun Technologies sight is ideal. Perception of reticle markings is largely dependent on the individual user. In my case, dots of Aimpoint T-2 and Holosun HS403GL remain dots, while in case of Vortex Sparc II and Sparc AR they get slightly blurred. Thankfully not so much as to hinder my aim. Perception of dots is very individual trait, it’s good to check the sights prior to purchase.
Holosun also produces reflex sights with M .R.S. (MULT I R E T I C L E S Y S T E M)  allowing selection of targeting reticle. Available options include : 2 MOA dot, 2 MOA dot in 60 MOA

Changing HS403GL mount is done by removing the screws at the bottom side of the sight with the smaller torx key. There are two mounts in the set, high and low. Screw placement is consistent with the standard introduced by Aimpoint T-1. This ensures compatibility with similar mounts from other producers. Mounts are adapted for installation on a universal rail interface (Picatinny/MIL-STD-1913) or newer NAR (NATO Accessory Rail, defined by STANAG 4694). They are mounted on the rail with a screw-tightened clamp that uses the bigger torx key included in the set. After picking the location for the sight, I suggest placing small amount of thread- locking liquid on the screw. The next step is placing HS403GL on the rail and tightening the screw. Remember to push it as far forward as possible within the selected indentation of the rail. This will reduce chance of losing the adjustments.
High mount provided together with Holosun HS403GL sight provides lower 1/3 co-witness. This means that any mechanical sights installed on the weapon should be visible in the lower

HS403GL mounts are installed on interface rail via a clamp that is tightened with torx screw. People often replacing their sights can get suitable QD mounts

Time for zeroing the sights. It can be adjusted within range of 50 MOA (100 clicks). Clockwise turn moves the reticle right or up, 2 MOA dot allows for precise aiming while being big enough for the shooter to notice it immediately after entering the right position depending upon knob used. Knobs clicks are felt and heard easily, with each click moving the dot by 0.5 MOA. After removal of low-profile caps, the user gains access to adjustment turrets. The right one is responsible for horizontal position, the top one moved the dot along the vertical axis. The caps themselves have the right shape to help turn the turrets during their adjustment. It’s important to note that the turrets themselves are unlabeled, without information which direction they have to be turned. Instead, the producer placed hints inside the caps, arrows with letters R (Right) and U (Up), informing of the reticle movement. This solution only works when the original caps are present. The turrets can be turned with screwdriver, small coin, or cartridge rim. Using Frank Proctor’s targeting system I managed to adjust the sights in a few shots.

2 MOA dot allows for precise aiming while being big enough for the shooter to notice it immediately after entering the right position

Holosun Technologies introduced in their reflex sights solution that is not present in Swedish constructions. I am speaking about Shake Awake system, which puts the sight into a sleep mode after preset amount of time, with default being 8 hours. Part of Shake Awake system is an accelerometer which wakes up the device with a move. Light shake is enough for HS403GL to return to the reticle brightness level it had before going dormant. Time before entering sleep mode can be set between 0 and 12 hours. To do so, you need to push and hold plus (+) button for 3 seconds. The light dot will blink multiple times, with number of pulses representing the current value of delay before sleeping in hours (it should blink 8 times with standard setting). At this moment pressing plus (+) or minus (–) buttons will increase or decrease the delay. Each click will adjust the delay by 1 hour and will be confirmed with the dot blinking once. After the desired delay is set, the plus (+) button has to be pressed and held for 3 seconds to confirm it. Setting the delay to 0 turns off Shake Awake mode, keeping the sight active until turned off. Is the Shake Awake function indispensable? I can’t decide. I would replace battery every 2 to 3 years anyway. Additional electronic part is another element susceptible to damage, though it haven’t failed for now. It has to be noted that even after the full turn off by pressing both buttons, HS403GL sight will remember the last brightness setting when turned on again.

During the test of Holosun Technologies red dot sight I shoot around 2 thousands of .223 Remington GGG bullets. Most of the time I fired GH15 rifle with 10.5 inch/267-mm barrel, based on AR-15 platform. Additionally, we tested HS403GL sight mounted on Grot S16 FB-M1. We haven’t noticed any misalignment of the targeting dot and the sight never turned off on its own. HS403GL sight cooperation with EOTech G33 magnifier went smoothly and allowed for increased accuracy. Thanks to small size and low-profile caps on adjustment turrets and battery socket, the red dot sight did not restrict the field of vision. Aiming was quick and intuitive. Without parallax effects shooting only required placing the dot over the target and pulling the trigger.

Holosun HS403GL sight was tested primarily on Kraków-built 5.56-mm rifle Gunshelp GH-15. The sight survived 2000 shots

The sight was also tested on Grot S16 FB-M1 rifle. High mount allows for use with mechanical elements visible in lower 1/3 of the lens

I am not one of the people who value aesthetics above all else and demand their weapon to look like new all the time. I am forgiving about occasional scratches that appeared on the body of the tested sight and consider them normal signs of use. It’s worth noting that even in the conditions of low light and high reticle brightness we weren’t able to notice the glow of the reflected dot on the front lens when looking from the front mere four meters away. While it is of little importance for a civilian user, it gives a taste of tactical professionalism. Holosun beat competition here – red dot sights of other companies gave glow noticeable from more than a dozen of meters. Ignoring slight surface abrasions, installation and removal of the sight while switching Tilted frontal lens prevents light reflexes. Image in the sight itself remains clear guns had no impact on the screws. Torx indents weren’t damaged in any way. If you want to keep the sight mounted on a single gun, use a bit of thread-locking liquid and screw it tightly. If you want to switch optics often, getting a QD mount would be good. Thankfully, Aimpoint T-1 standard mounts fit Holosun HS403GL. I am worried about longevity of rubber lens cover. They are almost identical with those used by Aimpoint T-1, and similarly don’t build my confidence. Their construction makes them easy to lose but for now, they play they role. Instead of putting them into pocket or hiding inside the bag, I’d rather leave them below the sights to reduce risk of losing them

Tilted frontal lens prevents light reflexes. Image in the sight itself remains clear

Rubber lens cover are connected to each other and are all around unexceptional. It’s the best to keep them on the sight’s base. They don’t interfere with firing while being kept safe

HS403GL was not spared during the tests. It is covered with scratches and abrasions. None of the incidents affected its operation, nor was there any loss of adjustments

The reflex sight’s tiny size leave a lot of space for magnifier and additional folded iron sights

Holosun Technologies Paralow HS403GL sight is relatively cheap. SpecShop offers that model for 250 EUR. The sight is usually in stock, and the set contains everything needed to mount the device on any weapon with NAR/Picatinny rail HS403GL is characterized by high brightness, comfort of use, memorizing intensity adjustments, and interesting sleep mode. I am confidently recommending this reflex sight for sport, entertainment, and training Rubber lens cover are connected to each other and are all around unexceptional. It’s the best to keep them on the sight’s base. They don’t interfere with firing while being kept safe 18-03/04 [ MILMAG.EU [ 065 purposes. Would I take it for war? Well, my positive impressions of this sight aren’t enough to overcome reputation of Aimpoint models and IP67 protection isn’t enough to recommend HS403GL for active combat duty. Personally, I am not going for a war and will keep using this red dot sight on my weapon. I am very content with its utility. It has excellent ratio of quality to price and its construction is well though and well polished. Battery longevity, Shake Awake system, clear lens, and two mounts are additional reasons to select this reflex sight.

This article was originally published on MILMAG 03-04/2018