Review: Holosun HE509T-RD Closed-Emitter Red Dot

posted on November 29, 2020

In the world of pistol-slide-mounted red-dot sights, the vast majority are of the open-emitter design. This is, for lack of a better word, the “standard” when it comes to pistol red dots—basically, the unit resembles an “L” on the slide, with a glass or plastic lens jutting skyward just behind the ejection port. The LED emitter is located rearward, projecting some sort of reticle, dot or other aiming device onto that glass or plastic, and the unit typically is secured to the slide through a pair of screws roughly in the middle.

Under certain conditions, though, it is possible for the emitter to get blocked—dirt, dust, rain, snow, etc.—which would result in a less-than-ideal sight picture, to say the least. One solution is to completely enclose the sight, much like the red-dot you might put on a carbine. Holosun’s HE509T-RD brings the enclosed-emitter sight to your handgun in a 2-ounce, titanium-clad package that uses an industry-standard footprint (RMR) to attach. The HE509T-RD has two reticle options available, a 2-MOA red dot and a 32-MOA/2-MOA circle/dot combination.

It’s worth taking a closer look at the attachment method, as it differs from a standard pistol-slide-mounted red-dot sight. Because the emitter is closed, of course, it can’t be mounted like an open-emitter sight, where screws go through the unit into pre-drilled holes on the slide (well, I guess you could, but you’d have screws running through the optic, which would be awkward on many levels…)

The HE509T-RD solves this dilemma by attaching, carbine-style, to a plate using a simple clamp screw. Attach the plate to the pistol slide, then attach the sight to the plate. The clamp screw features a lug that fits snugly onto a milled slot in the plate, keeping the sight quite secure.

Once secured, there’s little reason to have to mess with the HE509T-RD. The battery tray is accessed via a drawer, so there’s no need to remove the optic to swap batteries; given the impressive 50,000 hours of battery life (on setting 6 of 10), you shouldn’t have to replace the CR1632 battery terribly often, anyway. There’s even a solar panel atop the unit to provide emergency power in the event of battery failure.

Ten visible brightness settings allow a range of options, and there’s even two settings compatible with night-vision. Add to this Holosun’s “Shake Awake” feature, where the unit powers down after a period of inactivity, but is instantly on at the slightest motion, and that 50K battery life starts looking realistic. That’s more than 5½ years if the unit were to stay on the whole time.

In use, the HE509T-RD functions like, well, pretty much every other pistol-slide-mounted red-dot sight. Zero the dot using your distance and method of choice, with clearly labeled, click-based dials to adjust. Clever engineering? The elevation and windage dials use a small center slot to rotate, and it’s the same size as the battery drawer. Holosun even gives a tool with the T10 Torx head for the clamp screw and the proper size slotted screwdriver on the other side for all adjustments needed. Once zeroed, well, you’re off and running.

For testing, I ran the HE509T-RD on a Smith & Wesson M&P9 M2.0 Compact 4-inch Optics Ready pistol. Now, everything being equal, I would have preferred to have run the optic through at least the rudimentary 250-round test I subjected other pistol-mounted red dots a while back; however, with the current state of 9 mm ammunition, I’ve limited range sessions to a couple shorter visits of 50 rounds.

The HE509T-RD was close enough to perfect at 10 yards I didn’t need to adjust it, and over the small number of rounds fired, no change in zero was observed. Given that the less expensive HS407C V2 passed the 250-round test with no problems, I expect the HE509T-RD to do the same. I’ll be bringing it to the range in future trips, and will report back should anything change. I don’t expect to have anything to report.

On a side note, I opted for the single 2-MOA dot for my reticle. It’s a personal-preference thing; I’ve tried circle-dot reticles on pistol-mounted dots before and never really warmed to them; I’d guess it’s because I expect that sort of reticle on a carbine. In the case of the HE509T-RD, changing the reticle is stupid-simple: Press the “-“ button (decrease brightness) and hold for 2-3 seconds. Voila! You’ve changed the reticle.

For an MSRP of $506—and an “off the shelf” price about $100 lower—the HE509T-RD is a solid option. With the two reticles, it can serve equally well as a pistol dot or a carbine/shotgun dot, mounting securely and delivering literally years of battery life on a relatively inexpensive and easy-to-source coin-type battery. It’s a solid option for a pistol-slide-mounted red-dot optic.


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