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Product Review: Holosun HE509-RD Enclosed Red Dot Sight with ACSS Vulcan Reticle

Updated: Nov 13, 2023

What's the deal with enclosed red dots anyway? What the heck is the ACSS Vulcan Reticle? Do I want this mailbox looking optic on my gun? Stay tuned to find out.



ACSS Vulcan Reticle

Vulcan ACSS Reticle

The Holosun HE509-RD is yet another addition to the red dot market but this one is a little different than what you might be used to. This optic features an enclosed emitter unlike many other optics. This means that the big boxy housing protects the laser emitter for your dot in contrast to something like a Trijicon RMR. In addition, it features the new ACSS Vulcan Reticle. The Vulcan Reticle is a big step away from the usual plain ol' red dot most optics feature. It is designed to decrease the time it takes to pick up your dot and improve dot acquisition in unconventional shooting positions. Does it work? I wanted to find out so I got one and threw it on my primary handgun, a Shadow System DR920 Elite.

My First Impressions

This optic proved a little tricky mounting to my DR920. It mounts with a mounting plate and I had to order new screws to fit the DR920. My understanding is that with many other standard optic cuts it works more easily. If you are considering this optic I would do a little research and make sure it will fit your firearm of choice.

Once I got the optic mounted I was initially...unsure. It certainly doesn't look like many other optics out there and it does sort of look like a microwave sitting on your gun but it actually grew on me and now I rather like it.

I really like that you can replace the battery without unmounting the optic. There is a little tray on the side of the optic which you remove to replace the battery. No need to re-zero which is a big plus in my opinion.

The optic also features a tiny solar panel on top that I believe also serves as a light sensor for auto-adjusting your reticle brightness. I do not like auto adjusting reticles so I turned that off and I'm not really sold on the solar aspect but I figure if it improves the battery life at all that's a good thing.

The optic itself seems very durable and I have not noticed any shift in zero. Quality wise I had no issues with it and comparing it to the Trijicon RMR I had on my gun before there were some immediate improvements. For me the RMR window felt very small, especially with the addition of suppressor height sights. With a perfect draw and presentation I could find the dot quickly but under recoil or shooting in awkward positions I would often find myself losing the dot and having to re-acquire it. The window on the HE509 is much larger and it features a chevron instead of the traditional dot. It also has the star feature of the ACSS reticle, a large 250 moa reference ring around the outside edge of the optic window. The large ring around the outside is barely visible if you have the optic perfectly lined up but if you have a less than perfect sight alignment you will see a portion of the circle. Your brain quickly recognizes how to align the sight to complete the circle, bringing your chevron reticle to the center.

reticle explained

How I tested it

I've had the HE509RD for around 6 months and have shot several thousand rounds using it. I've used it in 100* weather and down to below freezing temps with snow. It has been subjected to thousands of draws and its size and position means it has been used to rack the slide hundreds if not thousands of times. I have not purposely tried to break the optic with any destructive testing as this is my main carry optic and I paid for it myself however it has held up fine and at this point I would trust it as a carry optic.


For me the biggest pros to this optic are the large window, the Vulcan Reticle and the enclosed emitter design.

I attended a Warrior Poet Society training class using my RMR and then an advanced handgun class with this optic and noticed a drastic improvement in my ability to track my dot (chevron in this case) through recoil and on presentation. This was due to a combination of the large optic window and the reference ring with the ACSS reticle.

The large reference ring really does help you pick up the dot and when shooting from uncomfortable positions it makes a big difference. Shooting from a nice standing position doing dryfire is one thing but when you are shooting under or around obstacles it is much more difficult to get your sights lined up perfectly. The large reference ring does decrease battery life but if you replace your battery annually as I do that shouldn't be a problem. If you don't like the ring you can always turn it off. The HE509 does have a shake awake feature to conserve battery life. If you leave the optic sitting for awhile it will turn off and then turn back on as soon as you touch it. It is very sensitive and I've never not had it turn on.

The next big pro for this optic is the enclosed emitter design. As a cop I carried an RMR and never really had an issue with the open emitter. Occasionally lint and dust would end up in the window but I never had an issue with the dot disappearing. With that being said I worked in an area that had good weather almost year round, no snow, and little rain. When everything is going well an open emitter optic is just fine. When I moved to a place with rain and snow I quickly learned the downsides of an open emitter design.

Open emitter red dot

My lovely wife demonstrating what happens when you mix snow with an open emitter

As you can see from the image it only takes a little bit of snow to completely obscure the window and cover up the emitter. Rain can do the same thing and leave you with a blurry mess. With an enclosed emitter you can simply wipe moisture or debris off the window and you are good to go.

An ACRO red dot. Wipe the snow off and it will work just fine


On the whole I really like this optic so I have to be pretty picky to come up with major cons. The mounting system is not my favorite. I would much prefer to be able to mount the optic directly to the slide without an additional plate. The closed emitter design means the optic is rather bulky and weighs more than many red dots. It has worked fine in my holsters but I could see it not working in some optic cut holsters if they are more designed for something like an RMR.

I enjoy the ACSS Vulcan reticle but I'm not sure how I feel about the chevron instead of the traditional dot. According to Holosun you can use the chevron as a ranging device giving you hold overs for 25, 50 and 100yds and they describe the point of the chevron giving you a more precise aiming point. At first I really didn't like it but when you actually get to using it I quickly adjusted. The chevron can be placed over close-up targets like a large dot and the tip of the triangle can be used for more precise shots. I would prefer if the optic had the option of switching it to a standard dot but at the end of the day I think the chevron offers more utility and is arguably better, I'm just more accustomed to a dot.

The auto adjust feature works similarly to other red dots I've used. I'm not a fan as the optic can only measure the light right above it. If you have different lighting conditions at your location verses your target it can lead to serious issues as the optic might dim out your reticle because it doesn't know you are looking into a bright room or light source (like a weapon mounted light). Thankfully you can turn the auto adjust feature off and it has large brightness adjustment controls on the side of the optic.


The HE509-RD is a little on the expensive side for a Holosun optic at between $380-$450 depending on where you find it and if it is on sale. The industry standard RMR will set you back closer to $500 and there are many Holosun options for cheaper. With that being said those are not closed emitter designs and do not have the ACSS Vulcan reticle. Another popular closed emitter design, the Aimpoint Acro will set you back $600+. Overall I would say the price is fair for what you get. If the features specific to the HE509-RD suit your needs than I'd say the cost is justified.

***As of 12/31/22 there is currently a sale at Primary Arms for $382 for this optic, click here if you would like to purchase.

The Final Verdict

Overall I think this is a fantastic optic. It is durable, has an enclosed emitter for inclement weather, has great features and an innovative reticle. If you ever feel like the window on your current optic choice feels too small or cramped or you routinely find yourself looking for that dot the HE509-RD could be a great choice for you!

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