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  • Post last modified:January 8, 2024

In this comprehensive Holosun 507K X2 review, I will delve into its specifications, mounting options, reticle design, and compatibility with subcompact pistols.

holosun 507k on p365 top view

My objective is to provide an initial impression of the optic's overall performance range without subjecting it to excessive stress that could cause total failure, which most users aren't likely to encounter.

holosun 507k x2 on hellcat pistol

To evaluate if they are suitable for duty carry or only for use at the range, I have tested various red dot sight optics under normal usage conditions.

Let's check it out my likes and dislike about the 507K.

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Holosun 507K Core Specs:

holosun 507k x2 pov
  • Magnification - 1X
  • Reticle - 2 MOA + 32 MOA Ring
  • Adjustment - 1 MOA / Click
  • Brightness - 10 DL&2 NV (Features Lockout Mode)
  • Footprint - RMSc
  • Construction - 7075 T6 housing + Anodized
  • Submersion - IP67
  • Body Dimension -1.6" X 0.98" X 0.95"
  • Window Size - 0.58" X 0.77"
  • 1 oz

Holosun 507K Unboxing

holosun 507k x2 unboxing

You get:

holosun507 k x2 unboxing inside

It's basically a baby size Holosun 507C for sub compact handguns.

holosun 507k x2 angled view

Right out of the box, it looks and feel very solid and it's straight cut, thick lens frame and rounded corner edges are for diverting impact stress away from the lens to greatly increase durability.

No solar panel, and the rear sight cut is there to serve as a back up iron.

Who Should Buy This Optic

Holosun 507K X2 is mostly designed for subcompact handgun users, and it can also be used as an offset backup sight.

  • Subcompact conceal carry users
  • 1911 users
  • Any thin slide handgun users

Holosun 507K X2 In-Depth Details

Window Size

holosun 507k x2 rear view

The window size is: 0.58" X 0.77"

It is definitely smaller compared to a full size optic, and it has slight lens distortion around the edges if you pay close attention.

holosun 507k x2 front lens

The lens distortion feels like a 1.1X zoom, but it's not too distracting for aiming close range targets.

holosun 507k x2 pov
holosun 507k vs 507c sizes

See more Holosun 507K vs 507C here

Practice is required to get good!

Shooters with good draw presentations of a small sub compact pistol can pick up the dot fairly easily.

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The Holosun 507K X2 features the same 2 MOA dot + 32 MOA ring just like the Holosun 507C X2. It's big enough for shooters to pick up and especially for sub compact pistols with 1911 style grip angle.

holosun 507k x2 outdoor pov

32 MOA is definitely big enough to acquire even if the center dot is completely off center. The shooter can still see part of the ring as a reference to re-adjust to center the optic. 

When aiming with two hands extended all the way forward, the 32 MOA reticle felt like it covers up the entire FOV, but it's not a huge problem.

To change the reticle, the user simply just hold the "-" button for 3 seconds to cycle through the reticle modes. Without a manual out on the range, this is the only thing you need to remember.

If you still can't find the dot, we got couple unobvious tips you can check out to help you find the dot on pistol easier.

Battery Life

holosun 507k x2 battery access door

The battery compartment can be accessed from the side in an small tray (Use provided allen key to open).

It takes a CR1632 battery to power the sight, and it lasts about 50,000 hours.

holosun 507k x2 battery removed

It's plenty of battery juice to last you almost 4 years before consider changing it, but we highly recommend you to replace the battery every year just to top it off.

holosun 507c x2 battery tray screw

Just be careful with the screw because its very small. When swapping the battery, put it somewhere safe so you don't lose it.


holosun 507k x2 on handgun slide

Even though it's small, it's made tough specifically for small conceal carry handguns.

The body is made of 7075 T6 forged aluminum, the highest grade material for field grade optic up to date. The lens frame has that straight cut and the corners are rounded to withstand reasonable amount of physical impact and divert it away from the glass:

  • Drop
  • Repeated recoil to hold zero
  • Slide racking
  • Every day carry wears and tears

The Holosun 507K, being an open emitter red dot sight, is susceptible to debris entering the optic if dropped into muddy or wet snow, potentially obstructing the LED emitter and making it challenging to remove the debris.

sig p365 holosun 507k snow

On the bottom, there are mounting lug cutouts to secure the optic offered by various optic plates

holosun 507c x2 chwps plate for hellcat

Features Springfield Hellcat with CHWPS plate


1 MOA / Click is all you get with this optic. It provides plenty of adjustment for what it is designed for - CQB

The elevation and windage adjustment knobs are recessed to prevent accidental adjustment.

I found the turret easy to dial, but I always need to remember to bring the tool provided in the package to the range. Because I can't just pick up 

Holosun 507K X2 Footprint

holosun 507k x2 mounting lug slots

The footprint of the Holosun 507K X2 features Shield RMSc footprint. 

Unlike the Holosun 507C X2 that shares the same base as the Trijicon RMR/SRO, the 507K X2 DOES NOT share the same base as Trijicon RMR or RMRcc.

Glock 43x mos holosun 507K

So far the only complaints people have is that the footprint is close to a RMSc but not exactly due to the front and rear mounting lug slots. This means the user has to file down the lugs on the slide and do tons of DIY work before installing this optic.

Holosun 507k x2 on springfield hellcat

If you have a Hellcat, Glock 43X MOS or other custom sub compact guns, be sure to purchase appropriate mounting plates for this optic.

If you have a P365 XL, the good news is that the 507K X2 will mount directly to the P365 XL right out of the box.

For installing it on other sub compact guns, please check out CHPWS Plates

Use For Conceal Carry

holosun 507k x2 conceal carry

Is the optic small enough for conceal carry?

The Holosun 507K X2 is truly a carry optic for being slim and small. 

It only works with holster with optic cutout.

However, the only downside for an open emitter reflex sight is that dirt, hair, and other debris can fall into the opening while holster under your cloth even if you're a super clean person.

holosun 507k x2 conceal carry appendix carry

Overtime, things can build up without cleaning, can affect dot clarity or potentially block the emitter.

Final Verdict

If you have been looking for a duty grade carry optic for a sub compact size pistol, the Holosun 507K is a viable option.

The window size is just a bit slimmer than a full size red dot, but with the right grip and good draw presentation, the reticle is fast to acquire and just as good as any other reflex sights.

At this price point, the Holosun 507K X2 ($289) is the best compared to the Trijicon RMRcc, which will run you at least ~$500, and the RMRcc doesn't fit most MOS handgun slides unless milling the slide specifically for it.

If you want a simple 6 MOA dot, please check out the Holosun 407K.


  • 7075 T6 durability with rounded edges to divert impact stress from the glass
  • Great for carry
  • Non snag body profile
  • 32 MOA circle helps dot tracking even if the dot is slightly off center
  • Side battery loading without sight removal
  • Cons

    • Need a super small flat head for dial and battery tray access
    • Not 1:1 RMSc footprint, which requires modifying slides and buy adapter plates
    • Open emitter design is not weatherproof
    • Doesn't fit optic cut with rear recoil lugs