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Thread: HE508T | First impressions and initial range review, with comparison to RMR

  1. #1

    HE508T | First impressions and initial range review, with comparison to RMR

    Note: this is posted by the official Noisefighters account, but comments are being made by the owner of the company in an unofficial capacity and are not an official endorsement of any product. Noisefighters is not currently affiliated with Holosun nor any other optics company.


    My background: USMC combat vet with 1/6 SSP back in the mid 2000's. I really got into pistols after the military, though. I've been running pistol red dot sights (RDS) since 2011 with the first being the original Leupold Deltapoint with triangle reticle, based off a recommendation from Bowie Tactical Concepts in an issue of Custom Combat Handguns. That RDS was neat, but I didn't think it was durable enough for hard duty use. I have been playing with Sig's ROMEO1 ever since they released the protective steel shroud for it. I have had multiple experiences shooting with Trijicon RMR's but have never personally purchased one due to the small window size, apparent magnification / fisheye effect, and heavy green tint. I have not yet had a chance to try Aimpoint's new ACRO P1 closed-emitter RDS.



    I believe this titanium-housed, multi-reticle, RMR-mount using, 100,000 hour rated, solar- and battery-powered, relatively inexpensive product may be the best pistol-mounted red dot sight for duty and defense -- but only if it turns out to be as durable as the venerable Trijicon RMR in the long run.

    MSRP: $447.05

    Street price: ~$349.99 at Midway USA


    First Impressions:

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    Headline feature: it appears to be billed as the first titanium-housed pistol RDS. On the surface, it seems like an odd choice, since titanium is about 67% more dense compared to aluminum or magnesium used on competing pistol RDS. However, the tensile and yield strength, stiffness, hardness (throughout the entire structure, not just the surface), and fracture toughness of a titanium alloy can be significantly higher than an aluminum or magnesium alloy. Titanium also has a much higher natural resistance to the elements, as well, so corrosion should be minimized.

    What I think Holosun has done is potentially engineered a way around Trijicon's RMR's patented, superior hood design that absorbs shocks quite well, by instead using a tougher material to accomplish the same goal. It will be interesting to see what Aaron Dynamics (Sage Dynamics) finds out if he decides to review this thing.

    The window is slightly skinnier than a SIG ROMEO1 and Leupold DPP and is perhaps slightly shorter, but it doesn't seem like anything's really lost by using the HE508T's smaller window size versus those optics, because the housing is suitably thin and doesn't block much viewing space. The HE508T presents a similarly compact form on a handgun to the Trijicon RMR, yet it provides a significantly bigger and subjectively much clearer view than the RMR.

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    The window is recessed from the front limits of the housing, especially compared to the SIG ROMEO1, and this should provide significant protection from frontal impact. Based on the titanium housing, recessed window, and the fact that the less-rugged, aluminum-housed Holosun HS507C survived Sage Dynamics' torture testing, I would not hesitate to use this sight as a slide-racking tool if needed.

    The glass has a slight green tint, approximately to the same degree as that found on Leupold DPP and SIG's ROMEO line of pistol RDS. The green tint is not noticeable to me outdoors and is quite minimal indoors. Also, like most RDS, there is a separate red tint that can be observed through the window under certain lighting conditions that can cover large parts of the visual field, but it doesn't appear to conceal those areas, just tint all the colors.

    There is an apparent magnification (fisheye effect) to the window, noticeably higher than a Leupold DPP and SIG ROMEO1, but less than what I perceive a Trijicon RMR's and Trijicon MRO's magnification to be. The Leupold DPP and SIG ROMEO1 seem like a 1.02x, the HE508T seems like a 1.07x, and the Trijicon RMR and MRO seem like a 1.10x. These are subjective approximations based on lens distortion I can perceive, not scientifically measured. It would be really cool if an optical engineer could chime in and let us know if there's a simple way to measure this. The fisheye effect on the HE508T is right at the limit of what I can tolerate, and I'm very picky. At close ranges, my brain just ignores the fisheye effect on this optic. At distances of 25 yards and more, it seems to bother me slightly.

    As stated previously, the optic comes with a 1913-style low mount adapter installed, but it can be quickly removed. The HE508T uses a Trijicon RMR style mounting pattern and appears to fit RMR-type plates for the Glock MOS system / FN509 adapter plates / etc. This appears to be a superior setup than going with a proprietary mount like the Aimpoint ACRO P1 requires, but I'm not going to judge that one yet until I try it. Maybe the P1 is worth changing everything.

    Mine is currently mounted on a Glock 45 MOS using the excellent, low-profile C&H adapter plate V3. If you have a Glock MOS pistol without that plate, you are really missing out, as the additional thread engagement, slightly lower RDS height, two additional recoil lugs, no need for an RMR sealing plate (if running an RMR), and improved aesthetics make it the go-to choice.

    The obnoxiously bright, painted markings from Holosun's lower cost offerings like the HS507C are thankfully not included. The unit is branded on three sides but without any coloring, and on the right side are laser-marked (gray color) lettering showing the model name and serial number. The only current housing color offered is flat black. The coating does not scratch easily, and my testing showed that even moderate taps from a brass gunsmithing hammer could not leave permanent marks (they rubbed right off without any damage).

    Sight adjustments are conventionally placed on the right and top using click-style screws. It took more force to adjust the screws than any RDS I've ever tested, but it was easy to tell when one click was accomplished. I cannot complain about this system, because from what I can tell, there's no way for the screws to be accidentally moved in transit and they're unlikely to budge under recoil.

    Holosun quotes "up to 100,000 hours" of continuous use of the combined circle + dot reticle on the medium brightness setting using the on-board battery and "up to 200,000 hours" of just the dot reticle on the medium setting. FYI, 100,000 hours is exactly 11.4 years, but industry convention seems to round down that hour number approximately 10% before converting to an equivalent yearly rating, so I believe ~10 or ~20 years battery life (depending on reticle selection) is the way to look at the HE508T. As far as I know, this is the highest battery life rating of any powered red dot sight on the market and overtakes the Trijicon RMR Type 2's quoted 4-year rating, the Aimpoint T2's quoted 50,000 hour / ~5-year rating, and even the Aimpoint Comp M4's 80,000 hour / ~8-year rating. If you know of a longer-rated red dot battery life, please let us all know. Also, as stated before, I'm not affiliated with Holosun and do not know how they calculated this rating.

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    The HE508T also includes Holosun's proprietary "Solar Fail Safe" technology that includes a solar panel on top. According to the manual (if I read it correctly), the optic prefers solar power and will only switch to battery as necessary. In addition, the optic features "Shake Awake" technology that turns off the reticle after a user-determined time window of zero movement, and turns back on instantaneously with very slight motion. The user can select 10 minutes, 1 hour, of 12h of inactivity or completely disable this feature and ensure their dot only turns off with manual intervention. Regardless of time selected, the reticle will power back on at the same brightness setting as last used. Finally, when the battery is low (below 2.2 volts), the reticle will blink. I trust the "Shake Awake" feature to work after having tested it extensively.

    A "Multiple Reticle System" includes an EOTech-style 32 MOA circle reticle and 2 MOA center dot, but the circle (or the dot) can be disabled as desired. To me, it seems quite a bit faster to find the circle + dot reticle simply because it covers more viewing area. This could be especially helpful for new pistol RDS users, since the dot can jump around enough that the shooter needs to constantly hunt for the reticle. The option to turn the circle off is nice for those who just want a dot.

    Note: this optic comes with a red reticle, but a green reticle model (HE508T-GR) is coming soon.

    The HE508T uses a CR2032 battery that sits underneath the housing and requires the entire unit to be removed, and additionally requires a proprietary tool (included) for removal. While this is the same as the Trijicon RMR, this is not optimum, as the sight zero may be affected upon reinstallation. Fortunately, with a ~10 or ~20 year battery rating and a solar panel as the primary power source, this is not going to be a common occurrence.

    The optic is rated IPX8 for continuous waterproof immersion greater than 1 meter.

    The HE508T is quoted at weighing 1.76 oz, but I forgot to verify this before mounting it to my Glock 45 MOS. My apologies. I do not know if the weight includes the 1913-type rail adapter. I'll update this post if I ever remove the optic or get the info from someone else.

    There are 12 manual brightness settings (10 daylight and 2 described as night vision compatible). The highest setting is extremely bright, perhaps brighter than necessary for almost any condition unless one was shooting right into the sun.

    The brightness adjustment buttons are very small, unpainted, made of what appears to be a rubber-like material, are recessed, and have either a + or - sign molded in. I can manipulate them with thin gloves on (both leather pilot's / flight gloves and Mechanix-style gloves), but winter-style gloves make it slightly more difficult to adjust due to the small size. They are definitely not like the adjustable LED brightness RMR's with the huge buttons on either side, but perhaps this system is better for some folks because the buttons will not likely be accidentally pressed. I know that I've never accidentally bumped my SIG ROMEO1 (with or without steel shroud) buttons, and they're similarly sized. I think I'd prefer larger buttons, but it's not a deal breaker.

    There is also an auto-brightness setting. I found the auto-brightness system to work fine for casual range use but would definitely not recommend it for duty use, as the brightness at the shooter is used to calculate the reticle brightness, and that doesn't always match the target brightness.


    Initial Field Test:

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    I put a couple hundred rounds through the G45 MOS with the Holosun HE508T and it has worked flawlessly, without flickering or any unexpected behavior. I'll update this post if anything ever goes wrong.

    It appears to be a quality RDS, but no optic is perfectly reliable, I would always recommend using backup sights for duty use. For Glock MOS, my choice is the suppressor-height AmeriGlo GL-429 steel sights for an approximate lower-1/4 or lower-1/5 cowitness (they are quite low in the window), as their low, ~$45 price point and simplicity are appreciated.



    The Holosun HE508T beats the Trijicon RMR in terms of window size, reticle choices, power conservation features, and is ~25% less expensive while using the same footprint. The lens tint and distortion is minimal and should not be annoying for most everyone, unlike the RMR. Plus, the less-rugged, aluminum-housed version of this same optic, the HS507C, survived Sage Dynamics' torture testing with a partially-cracked window and still held a zero.

    This titanium-housed version may survive that testing without even a cracked window if it's been designed correctly. If it does survive without issue and the window / electronics hold up over the long term, it seems to me that it will no longer make sense for potential RDS owners to purchase the RMR over the HE508T for duty use due to the disparity in feature set and price. The one drawback versus an equivalent RMR that I can find is that the brightness adjustment buttons are quite small.

    I can also see RMR users upgrading to this optic due to the circle + dot reticle option. It's something you need to try before you swear it off. It appears faster to me to find the circle + dot reticle under both recoil and normal presentation simply due to the increased field of view taken up by the reticle. I may end up running some tests to see what speed improvement, if any, there actually is.

    As I haven't used an Aimpoint ACRO P1 yet, I hesitate to compare it directly and would prefer others chime in who've tested both. From the spec sheets alone, though, there are stark differences in terms of battery life, reticle choices, and size. Also, for concealment purposes, especially in the appendix position, the ACRO P1's design seems to lend itself to printing much more than a traditional open-emitter design. I definitely look forward to seeing how the ACRO P1 compares to the HE508T in the future.

    That's all I can think of right now. If you have any questions or need clarification on some point, let me know.


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    Shoot straight and Semper Fi,
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  2. #2
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    Jan 2014
    Nice review! BTW I just ordered some Noisefighters based on VoodooManís recommendation. Looking forward to them.

    How close is the form factor to an RMR? If you have a custom milled slide with a tight fit RMR do you think the Holosun would fit?

  3. #3
    TOLERATED BY STEPHANIE LittleLebowski's Avatar
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    Feb 2011
    Well done review, jarhead.

  4. #4
    Good post.
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  5. #5
    Due to the type of optic this is, can I safely assume it might be more friendly to those with astigmatism, like the RMR?

    If so...this is awfully tempting.
    Fredís Principle: The smartest of a large number of hamsters is still a hamster.

  6. #6

    Form Factor

    Quote Originally Posted by mkmckinley View Post
    Nice review! BTW I just ordered some Noisefighters based on VoodooManís recommendation. Looking forward to them.

    How close is the form factor to an RMR? If you have a custom milled slide with a tight fit RMR do you think the Holosun would fit?
    Thanks for trying out my ear pads. I really appreciate that


    The form factor is nearly exact in terms of X-Y (footprint) dimensions. In fact, the C&H adapter plate for MOS pistols does not distinguish between the RMR and the HS507C / HE508T. As stated earlier, it's a little bit taller, and the window size feels comparatively huge versus the RMR. However, the window seems about 85% of a Leupold DPP or Sig ROMEO1. I think it's just right.

    If one had their slide milled for the RMR, the machinist may have radiused certain edges in order for the RMR to fit exactly, and the corner radiuses on the HE508T may not line up perfectly. I don't have an RMR on hand to compare. That said, if the internet is to be believed, many people have been able to successfully transplant a Holosun HS507C right onto their RMR-milled slides... I'm guessing Holosun copied the radiused corners perfectly.
    Delivering the first gel-filled ear pads with relief cuts for glasses to pass through.
    No more headaches. Less noise.
    USMC combat veteran designed and made entirely in the USA.
    Direct: 616-226-3551 |Email:
    Based in Grand Rapids, Michigan

  7. #7
    Quote Originally Posted by Dan_S View Post
    Due to the type of optic this is, can I safely assume it might be more friendly to those with astigmatism, like the RMR?

    If so...this is awfully tempting.
    I'm not sure I'd consider it more friendly to those with astigmatism. I have insight into this because of a full thickness corneal transplant on one of my eyes, as it brings with it highly irregular astigmatism. Both this optic and the RMR project a reticle that appears quite distorted when I look through it with that bad eye. When the circle is enabled, the reticle becomes a much larger blob of distorted light, and it's more difficult for me to accurately aim. If I were using that bad eye with this optic, I'd just use the center dot without the circle, since the visual field would be less cluttered and easier for me to figure out where the actual center point is.
    Delivering the first gel-filled ear pads with relief cuts for glasses to pass through.
    No more headaches. Less noise.
    USMC combat veteran designed and made entirely in the USA.
    Direct: 616-226-3551 |Email:
    Based in Grand Rapids, Michigan

  8. #8
    Hmmm. Ok. Interesting.

    I thought at one point the RMR was regarded pretty well as an option for those with astigmatism.

    Not likely Iíll have a chance to try one out, and not looking to drop more money on stuff I canít use well. 😐

    Design looks fantastic though and Iíll look forward to updates!
    Last edited by Dan_S; 09-04-2019 at 09:57 AM.
    Fredís Principle: The smartest of a large number of hamsters is still a hamster.

  9. #9
    Nice write up. Mine is due in tomorrow and I feel a little better about my purchase already.

  10. #10
    Something I noticed with the Holosun 507, is the front lens seemed to scratch easily. Any thoughts on that aspect of this optic?
    Likes pretty much everything in every caliber.

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