TFB Review: Holosun 507K Mini Red Dot Sight

    An in-depth, hands-on look at one of Holosun's new slimmer pistol red dots, the 507K.

    An in-depth, hands-on look at one of Holosun's new slimmer pistol red dots, the 507K.

    In the early days following their founding just seven years ago, Holosun’s optics sat firmly in the “budget” category. I think it’s fair to say that in general they were not particularly highly regarded. Although some shooters liked them just fine, others certainly did not, and at first, they didn’t appear to be a threat to unseat any titans of the gun glass world. However, as is usually the case with companies who survive the struggles of their first few years, they’ve made notable improvements since their humble genesis, and have taken some pointed lessons learned. Holosun in 2020 is not the same as they were in 2015, and today ever more shooters are becoming believers in products they wouldn’t have considered in the not-so-distant past. Consumers have taken notice, as have competitors, with Holosun’s pistol red dots, in particular, seeming to be gaining a fair amount market share.

    The SIG Sauer P365XL comes optics-ready from the factory, with this easily-removable slide plate and rear sight.

    The SIG Sauer P365XL comes optics-ready from the factory, with this easily-removable slide plate and rear sight.

    I hadn’t made the jump to pistol red dots prior to my purchase of a SIG Sauer P365XL at the beginning of this year. I’d carried a night sight equipped Glock 19 for years, but in testing a friend’s P365XL I became intrigued. It offered easy concealability and maintained good capacity. Soon after, I brought home one of my own, and given SIG’s inclusion of an optics-ready slide, I elected to equip it with a red dot. Fortunately, this was right around the time of SHOT 2020, and at the show, TFB reported on Holosun’s upcoming offerings. Among these were two new mini red dots for slim-frame pistols, the 407K and the 507K. I decided to give Holosun a shot and placed my pre-order. After some unforeseen pandemic-induced supply chain interruptions causing several months of shipping delays, my new 507K finally arrived.

    Unboxing the Holosun 507K, with the red dot and other package contents laid out.

    Unboxing the Holosun 507K, with the red dot and other package contents laid out.

    Hands-on with the Holosun 507K:

    Upon unboxing, I began closely examining the unit. It was nicely compact, but I was pleased to find that the 0.58 x 0.77-inch viewing window didn’t feel too small or cramped. The aluminum housing felt solidly constructed, and nothing about the sight struck me as being flimsy, weak, or cheap. Thankfully, this optic definitely gave an initial impression of seeming well built. There were no apparent flaws, flexing, or rattling to be found. I used a food scale to check out the weight, and it came in at 0.9 of an ounce without the battery installed. Holosun’s specs advertise one ounce, so accounting for the CR1632 coin battery, this should be pretty dead-on. Comparing the sight’s width to that of my gun, the form factor looked to be a superb fit. Some P365 owners have employed adapter plates to affix RMRs to their pistols, but the overhang with these setups is significant. The Holosun’s lack of this issue was one of its key selling points for me.

    The diminutive optic's weight addition is negligible, as this food scale indicates.

    The diminutive optic’s weight addition is negligible, as this food scale indicates.

    TFB TV's James Reeves silently judges you through the 507K's multilayer coated glass.

    TFB TV’s James Reeves silently judges you through the 507K’s multilayer coated glass.

    Installation was a breeze. In no time at all, I had removed my SIG’s slide, backed out the two plate screws from underneath, and replaced the cover plate and rear sight with the Holosun 507K. The loss of factory rear sight was a non-issue, as the Holosun has an integrated backup sight. The multi-reticle system, offering the choice of circle-dot, circle only or dot only reticles, was easy to change and I liked the flexibility it provided. The easily-accessible battery tray is a definite boon, and doesn’t require removing the sight from the slide to change batteries. That said, with an advertised battery life in the 50,000-hour range and a shake-awake feature that I happen to love, it shouldn’t chew through batteries regardless of how easy they are to swap out.  Holosun’s website shows some other innovations as well, like their Solar Failsafe technology, Super LED technology, Multilayer Coatings, and the use of Titanium components in some of their products.

    Beyond the sight’s features, I was interested to see how its addition to my SIG would affect concealment. Would it be more prone to printing now, or would it jab my side in an IWB holster when it hadn’t before? Testing out a variety of holster positions while standing, sitting, walking, driving, and more revealed no problems. It felt every bit as pleasant to carry with the 507K as it had without, and still concealed even more effortlessly than my Glock 19 with iron sights. By every metric I’d tried at this point, the Holosun 507K was a winner. However, the most important facet of testing still remained: shooting with it.

    One common gripe about some other companies' red dots is that they require you to remove the optic to change the battery. Holosun eliminated that issue with this side-opening battery tray.

    One common gripe about some other companies’ red dots is that they require you to remove the optic to change the battery. Holosun eliminated that issue with this side-opening battery tray.

    The range-ready finished product.

    The range-ready finished product.

    A local gun store, RifleGear, had just moved to a new facility that included an indoor range, so for the Holosun 507K test session, I went to try it out. Though I usually prefer outdoor ranges with the freedom of open bays rather than indoor single lanes, this range is nice and more than sufficient for my purposes in this case. If you’re in the Dallas area, check them out. Before the range trip, I had started my zero process at home by “lollipopping” the red dot on top of my SIG’s front sight post, just as a reference off of which to adjust. This method is championed by Aaron Cowan of Sage Dynamics, who is widely regarded as one of the top subject matter experts regarding pistol optics. Using this as a starting point, once on the range I fired my groups and made the necessary windage/elevation adjustments to hone it in properly. The 507K’s adjustments dial in with .5 MOA clicks, which can be positively heard and felt using Holosun’s included tool that you can see pictured above. That same small flathead side of this tool also opens the battery tray, and the other head is a T10 Torx which fits the screws securing the dot to the gun’s slide. It didn’t take long before the number of clicks shrank to two at a time, then one, then none, and 507K and P365XL were working together superbly. The process for adjusting my eye’s focus, from managing a two-plane sighting system to focusing through the reticle’s single plane and onto the target, all proved more than manageable. In seemingly no time at all (although I’m far from a top pistol shooter and can certainly stand to undertake more training), I was able to produce eminently satisfactory results with close groupings and effect consistent, solid hits on target.

    Although it had previously looked good in theory, my real 507K trial began here.

    Although it had previously looked good in theory, my real 507K trial began here.

    Zeroing and testing the 507K on my P365XL.

    Zeroing and testing the Holosun 507K on my P365XL.

    "Smile and wait for the flash!"

    “Smile and wait for the flash!”

    I had anticipated that this transition would be challenging. I was prepared not to like the dot, or for it to take a fair bit of time to achieve substantive acclimation. For more than a quarter century, since childhood when my dad first let me try his old Ruger .22 revolver once I was ready to graduate from my trusty Daisy Red Ryder, I’d only ever shot pistols with iron sights. Even well into adulthood, in Army training with the M9 or concealed carrying my Glock 19 and all the other pistol shooting I’d done to this point, it was all irons. From body mechanics, sight picture/target acquisition, and all of the elements that comprise successful handgunning, I thought the re-training process was going to be an onerous task. Although there is still progress to be made, I am exceedingly pleased to be able to report that the early stages of this foray have been exponentially easier than I’d suspected. I wholeheartedly believe that a good portion of the credit for this goes to the remarkable quality of the Holosun 507K. While no piece of gear is going to be perfect for everyone and you can nitpick even the best of equipment, as far as I’m concerned Holosun got this one very right. I am absolutely keeping it on my EDC gun for the foreseeable future.

    In all, for me personally the Holosun 507K is definitely a "go" so far, and I am hopeful that it holds up well over time.

    In all, for me personally the Holosun 507K is definitely a “go” so far, and I am hopeful that it holds up well over time.

    My only two question marks at this juncture are these: 1. will it hold up over time with thousands of rounds fired and prove to be durable enough in the long term, and 2. as new diminutive red dots continue to come out (does anyone else think a miniaturized version of the RMR is overdue? turns out I wasn’t the only one, as Trijicon announced their RMRcc between the time of this article’s writing and its publishing) could the 507K find itself outmatched by a newer competitor in the near future? Both of these could become an issue down the road, and only time will tell. Until/unless we reach that point, I can absolutely recommend the Holosun 507K without any reservation. Given that the RMRcc has to be removed to change batteries like its big brother, doesn’t have the features of the Holosun (such as multiple reticle options), uses a proprietary footprint requiring a separate mount, and costs significantly more, I still think it’s likely that the 507K keeps the edge for now. Ultimately, in my view, the 507K is a well-designed feature-rich unit that does exactly what you want it to do, and at a good value for your money. Will you love it as much as I do? Will time and extended experience reveal inadequacies that aren’t yet apparent? Maybe, maybe not – and of course shooter preference has plenty to do with gear selection. But if you’re considering an optic for a slim-frame handgun (which you should be), Holosun’s red dots absolutely deserve to be in your consideration set. I’m certainly keeping mine. Bottom line, do yourself a favor and check out this spectacular little optic. Stay safe, and I’ll see you at the range.



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    Will P

    Former US Army infantryman, lifelong hunter and hobby/sport shooter. Perpetual firearms student, always seeking to become better and learn more. Interested in all shooting disciplines and passionate about all kinds of guns. Contact on Instagram: @WillTFB


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