When looking to put an optic on a Glock 48, my options were limited. Sure, I could throw an adapter plate on the gun for a full size optic, but that starts to defeat the point of a slimline pistol. Luckily, a few companies make reputable options for this size of handgun. This leads us to Holosun and their K-series of optics. How does the Holosun 407K stack up to the competition?
Construction and Use of the Holosun 407K
The Holosun 407K is a fairly conventional, open emitter, pistol mounted optic. Using the Shield RMSc footprint, two screws pass through the top of the optic to attach it to your slide. This optic is designed for use on pistols with slim slides, such as the Glock 48, S&W Shield, or a 1911. As such, it is overall smaller than something like the Holosun 507C, hence its “K” designation. As with other optics in the “X2” line, batteries are now side mounted in a removable tray, simplifying battery changes.
The rear of the housing features a built-in rear sight notch, designed to cowitness with factory front sights. This notch is non-adjustable, and very wide yet shallow, making for a rough sight picture. It’s certainly useable, but far from ideal or precise. The inner edges of this rear sight notch are somewhat sharp, which can irritate skin if they come into contact. I still recommend a dedicated rear sight in addition to this notch as a supplemental aiming device.
Battery Life and Function
Holosun claims up to 50,000 hours of battery life on a single CR1632 battery. This has not proven to be the case in reality, with Duracell batteries lasting under a year. Battery life will widely vary based upon your brightness level, environmental factors, and more. I highly suggest regularly swapping batteries at least every six months to avoid any unexpected failures. Luckily the side mounted battery tray makes changes a breeze. To date, my zero has not been impacted by swapping batteries.
Unlike some full size options, the 407K does NOT feature a solar panel for supplemental power. It does however feature Shake Awake, helping to conserve battery while allowing it to turn on automatically when jostled. This helps preserve battery life, but don’t rely upon it to keep you in the clear. To date, the K-series from Holosun is the only optic to surprise me with an unexpectedly dead dot. The delta between their stated battery life and what I get in reality is significant. I believe parasitic drain is an issue here, killing optics held in storage. Again, swap your batteries at least every six months, if not quarterly to avoid any nasty surprises.
Controls and Adjustments on the Holosun 407K
Adjustments
Zeroing is typical Holosun fare. On both optics I get inconsistent clicks for windage and elevation. Sometimes adjustments are very tactile and audible, while others sneak by like mush. This is also inconsistent across other K-series optics I’ve handled over the past few years. Holosun features 30+/- MOA of windage and elevation adjustment on the 407K, which has proven to be insufficient to attain zero with some guns such as the Taurus 856 TORO. While a proper zero can typically be reached, it is not as easy as you may experience with other manufacturers.
Unlike zeroing, brightness adjustments are positive across the board. There is a distinct click when lightening or darkening the reticle, with noticeable shifts when looking through the glass. The 407K seems to get brighter than some larger models, and is completely sufficient for the powerful Nevada sun. Users can lock their brightness setting to avoid accidental adjustments, though I have not used this feature.
Reticle and Glass Quality
Glass quality is surprisingly good on the 407K, especially when compared to other offerings from Holosun. While not quite as good as an Aimpoint ACRO or Steiner MPS, it is head and shoulders above my 507C’s or 509T. There is very slight distortion around the edges of the glass, but the 407K again leads its larger brothers here. I do have some difficulty cleaning areas where the housing and glass meet, but this does little to impact the user experience.
Both of my Holosun 407K feature a 6MOA reticle. This single dot is incredibly crisp, making a perfect circle like using a hole-punch on paper. The larger reticle is easier to see in direct sunlight, and at lower brightness levels than smaller options. This results in a more refined sight picture, cutting out the starburst effect, providing greater precision, especially on smaller targets. There are 10 daylight, and 2 night vision friendly settings, though I have not tried this optic under night vision.
Range Time with the Holosun 407K
Range time with the Holosun 407K is divided between three different serial numbers. One is milled into a Glock 48 slide, another atop a G48 MOS using a C&H Precision plate, and a 407K-GR (green reticle) on a S&W Shield Plus chambered for 30 Super Carry. In total, over 5,200 rounds have been fired between the three optics. The first optic was milled onto the slide by ATEi in the Fall of 2021, second being mounted in Summer of 2022, and third in Fall 2023.
Below are the specific round counts:
1,929 Rounds fired on milled slide
- 75x Aguila 124gr FMJ
- 50x Winchester White Box 115gr FMJ
- 100x On Target 115gr FMJ
- 50x Blazer Brass 115gr FMJ
- 250x Speer Lawman 124gr FMJ
- 250x Magtech 124gr FMJ
- 441x Blazer Brass 124gr FMJ
- 700x Federal American Eagle FMJ
- 11x Federal HST 124gr JHP
2,508 Rounds fired on MOS slide
- 200x Aguila 115gr FMJ
- 280x On Target 115gr FMJ
- 100x Winchester White Box 115gr FMJ
- 209x Federal American Eagle 115gr FMJ
- 25x Sellier & Bellot 115gr FMJ
- 705x Federal American Eagle 115gr FMJ
- 874x Magtech 115gr FMJ
- 25x Fiocchi 115gr FMJ
- 40x On Target 115gr FMJ
- 50x Blazer Brass 115gr FMJ
977 Rounds fired on 30 Super Carry, S&W Shield Plus
- 100x Federal American Eagle 100gr FMJ
- 705x Remington UMC 100gr FMJ
- 105x Blazer Brass 115gr FMJ
- 5x Remington HTP 100gr JHP
- 20x Hornady Critical Defense 100gr XTP
- 22x Federal HST 100gr JHP
- 20x Speer Gold Dot 115gr JHP
As is expected with the smaller window of K-series optics, losing the dot is more likely than on larger options. This does little to impact performance of the shooter, but is worth noting. Any changes in split times are attributed more so to the smaller pistol rather than the optic.
In terms of accuracy, there are virtually no differences here. The combination of Glock 48 and 407K has yielded repeated scores of 49/50 at 25 yards on a B-8 Repair Center when paired with quality ammunition. In short, the 407K stands toe-to-toe with its full size brethren, despite its small stature.
Durability
Since mounting, these guns have been used in a variety of courses to include FPF Training Street Encounters, Citizens Defense Research Tests & Standards, and more. This is in addition to regular range time, and consistent carry in a variety of seasons and environments.
It has seen temperatures from below freezing to 115+ degrees, been rained on repeatedly, experienced blowing sand, and more. To date, the 407K has proven to be reliable and robust, providing zero issues mechanically nor electronically. All screws have remained tight, showing no signs of loosening under recoil.
Final Thoughts on the Holosun 407K
Overall the Holosun 407K has repeatedly proven itself as a reliable optic. While their full size offerings may not be my favorite, the K-series is one of the best in the business for these smaller sized optics. I would love to see the company add a little more elevation adjustment across the board, but that isn’t a deal killer. If you are looking for something to throw on a slim pistol, give these some serious consideration.
MSRP on the Holosun 407K is $258.81 as of the time of this writing. For those wanting something slightly different, Holosun also offers a green reticle for $276.46.
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