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UM3 Pistol Sight Mount

Have you ever wanted to mount a red-dot optic on your pistol but didn’t want to send your slide out to be milled? Well, now you can attach a Picatinny rail mount to most pistols with a front attachment rail (a 1913-style or similar), without gunsmithing. All you need is a UM3 sight mount . . .

Getting your slide milled for red-dot sight can run you around $200, once you add shipping. For under $100, you can get a UM3 mount that will clamp on — no machining necessary. If you’ve never shot a pistol with a red-dot, I suggest you try something one first before spending a bunch of money and getting your slide drilled. A UM3 will allow you to do that without a big investment.


This installation of the sight mount is pretty simple. Just slide it on your pistol’s rail while holding down the spring-loaded detent. Once the mount is in the right spot, just release the detent lever and the mount is held in place. I tested one out on my GLOCK 17, and it went on smooth, though it was a tight fit. It’s not something that you want slopping around, though.

UM3 Pistol Sight Mount - Top View

The mount is split on the top down the middle of the Picatinny rail to make installing the mount easier on a variety of pistols. To mount your red dot once the UM3 is attached, pinch the two halves together, mount your sight and clamp it down as you would on any other Picatinny rail, tightening until both halves are fully closed.

I’m using a Vortex Razor for my testing and it attached to the UM3 just fine. The clamping process is a little fiddly, though. Since the rail is split on top down the middle of the Picatinny rail, you have to squeeze it together to place the red-dot and clamp it tight. UM advises that you tighten your sight until both halves of the rail meet. I had to use a pair of pliers as it was snug on my G17. Once the sight is mounted, the whole affair sits solidly on your pistol.

As for overall fit, the rail fits OK. On my GLOCK 17, it seems to be a touch off center, thought it’s hard to tell for sure. The mount clamps onto the pistol’s accessory rail pretty tightly, and doesn’t seem to wiggle around at all, so that is good. An updated list of guns the UM3 works with is here.


The UM3 is constructed of 6061-T6 aluminum and Type-III hard anodized. That means it should be durable, semi-scratch resistant and take a decent beating. The overall build quality is nice, there are no excessively sharp edges or major blemishes, etc.


So now that you have a red-dot mounted on your pistol, all sighted in and ready to go, how are you going to carry this setup Well, UM Tactical also makes a “universal” carbon fiber paddle holster with cutouts for the UM3 mount, the UMH3C.

UM3HC Pistol Holster

The UMH3C holster is a basic adjustable carbon fiber speed holster with no mechanical retention. It’s a universal holster that fits a variety of pistols, so it’s not really designed to be a run-around type of rig, though it seems to be well constructed and pretty durable. My pistol fits pretty tightly, so there will definitely be some break in time required.

I generally prefer holsters with some level of mechanical retention, but this one definitely works for playing around at the range, or other times when you may not need active retention. The holster uses a Blade-Tech adjustable paddle that will work with belts up to 2.5″ wide, a nice added feature.

UM3 Pistol Sight Mount with UM3HC Holster


With your red dot mounted, it works as you would expect it to, but, there are some gotchas with a setup like this. The primary one being that the sight’s height over the bore is pushing 2″. At distance that’s not too big a deal, but at closer ranges, your point of impact will be low. This type of thing really can come into play when trying to shoot around or over objects. Just something to keep an eye on.

Also, shooting with a red-dot takes a while to get adjusted to. There is less of a point of reference, so if you draw your weapon and don’t see the dot, you end up doing a little jiggling around to find it. It just takes practice to get used to it, and once you get it down, it’s pretty nice.

It took me about 10 rounds to get everything sighted in, and then, everything just works with this. I didn’t take it on and off of the pistol, but the sight stayed accurate between reloads, messing around with targets, holstering, etc.

UM3-Target-1 UM3-Target-2


UM3 Sight Mount MSRP: $99

UMH3c Holster: $69

Ratings (out of 5 stars):

Ease of Installation * * * ½
This is one of the easier accessories you could install on a pistol. The only “gotcha” is actually getting the optic on the 1913 rail because of the split. It requires a little “work.”

Build Quality * * * * *
The UM3 Pistol Sight Mount is solidly made with no rough edges and a simple design.

Functionality * * * ½
This mounting system works, but I wouldn’t consider it permanent for anything like a competition gun. I look at it more as a tester to see if you like a red-dot on your pistol, or if you want to move a sight between a variety of pistols.But as far attaching a red-dot on your pistol, it gets the job done.

Accuracy * * * *
The UM3 stays pretty accurate. In banging the pistol around a bit and firing it, the point of aim seemed to stay true.

Overall * * * *
The UM3 is a simple design that works. The UMH3c holster will fit a variety of guns with the UM3 mounted and gives you a way to tote your UM3 pistol-equipped gun around.

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  1. The fitment link is broken.

    I am somewhat interested in throwing this on my CZ-P09 and seeing what she’s capable of at longer ranges.

      • I’m not sure that’s an upgrade per se. Polymer vs Steel and all that… I was looking at a P-01 but didn’t know if it would be worth the money.

        I love the P-09 as a range gun. Lots of capacity, grip fits my paws, decent SA trigger that can be easily improved. Of the plastic 9mm pistols that I have tried, it shoots the best for me. Very affordable as well. I tried an XDM and a M&P first. The XDM shot pretty well, and didnt fit me. The M&P fit great and shot mediocre. The CZ fits great and shoots great. YMMV 🙂

      • Personally I find the CZ75B is better (funner) to shoot but my P07 is a little easier to carry. I don’t notice much weight “difference” but center of gravity between the two is a bit different, and I find the P07 “better” in that regards.

      • Groups were from about 7-10yds. I was pretty “bouncy” that day. I did take some shots from about 20 yds, everything was “on target” so to speak, but they were on a messy target (larger sighting in target) so don’t have any pictures from it.

  2. Sorry, but this is a big pile of NOPE. If you’re gonna RDS a pistol, do it right. If you’re curious about it before you do it, try someone elses, because this isnt going to give you a good comparison to a properly milled slide with an RMR that cowitness’ with the iron sights. Not even close.

    • This was never intended as a REPLACEMENT for milled slide setups, it was intended more for the sport shooting crowd (IPSC, steel etc.). Many high level open class shooters prefer the high mounting of a red dot sight because it gets their arms and the gun down lower out of their line of sight so they get a better view of the stage. Visual awareness of everything that’s going on downrange is critical at the highest levels of competition. Multiple USPSA Grand Masters have evaluated the UM mount and holster and found it to be just as good as their custom permanent mounts and skeletonized speed holsters–only it requires no modification to the gun, is far cheaper and is universal. One mount and one holster will have you set for almost any medium to full sized gun with a bottom rail. The holster interfaces with the mount, not the gun, so one holster truly fits any gun with the mount on it. The holster accepts any Blade Tech attachment (paddle, Tek-Lock, belt loop, etc.). Because of the mount’s “squeeze from the top” mechanism, on-and-off is easy yet it locks up solidly and returns to zero without the need for screws on the bottom. I’m not sure how the reviewer had such problems with his, I’ve used several of these on several guns and have had no problems. It’ll always be more solid on a metal framed gun than polymer, but that’s true of any frame-mounted scope mount. Even on polymer it returns to zero and maintains zero well enough for Grand Master shooters. From a home/self-defense perspective (not its intended role), yes the height of the mount requires some retraining to use effectively (many sport shooters have no trouble using iron sights in some matches and high-mounted red dots in others–the body learns to do what’s appropriate with sufficient training and practice), and most folks won’t be able to carry it concealed, but note that with this mount you have TRUE backup iron sights that you can see clearly underneath the mount even if your red dot sight is fogged or shattered. Also I’ve found personally that slide ride will kill virtually every red dot sight currently on the market except for the Aimpoint Micro (which is huge on a pistol and expensive) and the modified “bulletproof” Docters made by Dean Makkos of Docter USA, which are expensive (over $500). With the UM mount, because the red dot sight does not move with the slide, cheaper red dot sights survive fine and give great service (as long as you don’t routinely bash them on things). Respectfully I think a reviewer should spend more time with a product, understand its purpose and competitors and generally do more research before throwing up a review, although I understand the benefit of a basic “everyman” perspective. Sorry about the long reply but I’m friends with the developer of these products–but completely independent of that I think they’re great, cost-effective products that work a lot better and have more positive features than this review suggests.

      • I think I’d be concerned about visibility of the iron sights and the target in low light conditions. Could we get a photo of what the sight picture looks like using the iron sights with the mount installed?

      • I have this mount on my Glock G20 10mm and it’s the bomb. It’s much easier to mount and dismount than the reviewer insinuates. I have a Burris FF3 on it and also I have the holster. I find that the 2″ height is NOT a problem with close range shooting. I have mine sighted in at 50 yds and I intend to use my setup for deer hunting.

      • Thank you for the reviewer and for your long comment. This is a very good insight you give here to add to the review for a prospective buyer like me.

  3. Dead link for the new version.
    I think I’d like this if it had a screw or two to tighten the bottom.

    Nice review

  4. I’ve had a single side one for several years that came from Walther and fits several pistols. It clamps on the rail like a scope mount with 2 hex screws and seems to have no problems holding up to whatever I’ve slapped it on. As far as I can remember I’ve had it on H&K USP 45, CZ 40-p, Taurus PT-92 and a Walther p-22 without any real problems. It’s a nifty idea but makes the rig a bit cumbersome for anything other than playtime.

  5. Now, how sturdy is this? I ask, because I want to use a double side Picatinny QD mount, so I can mount my GLOCK to my AR-15. I want a VFG that has a light, a laser, and spits out .45 bullets.

  6. When I saw the picture at top, I thought that was the holster itself. I thought that was the worlds most unsafe holster.

  7. It’s not UNDER $100. It IS $100, using whole dollars. It may be under $100.00, but not $100.
    I’m not trying to split hairs or police grammar, but I don’t like manipulative terminology.

    I also don’t like calling “civilian disarmament”, or weapons legislation in general, “gun control”. It isn’t.

    (Then again, I saw $99.99 on only their website. There may be sales below MSRP elsewhere.)

  8. One of the :gotchas” with these mounts is the clearance over the slide.

    Most are designed to allow use of the existing iron sights in an emergency. All are designed to allow (at least) normal front sights to clear as the slide runs back during discharge.

    But the sturdier ones may not be designed to allow clearance for the REAR sight to pass through the mount when removing the slide. So the mount must be removed, making return to zero an issue when re-installed. This point is easy to overlook, but should be tested and discussed in any review.

    The UM3 mount may deal with this issue by making removal seem easy – “just” remove the optic and unclip the mount. But that also makes “return to zero” quite unlikely. Whether it returns close enough to zero is also worthy of testing and discussion.

    I know the Fab Defense USM is very stable in use, must be removed to clean the pistol, and when re-installed it accurately returns to zero . . . at least as far as my Mark 1 eyeball can determine lol. I don’t know about the UM3.

    A comparison of the UM3 and the Fab Defense USM focusing on (a) how stable, (b) clearance for rear sights moving forward, (c) ease of removal and re-installation, and (d) accuracy of return to zero after removal would be quite useful.

  9. I have an XD9 Mod 2 Subcompact (3″) and an FNH FNS-9 4″ that I thought this would work great for.
    Bought it… Doesn’t work for THESE guns. The designer of the little pressure clip forgot about all the companies that like to place the guns serial number down in this picatinny area.
    My FNS-9 has 3 notches but then do not have full, across, rails. So once clipped on past the first rail…. it just slides BACK and FORTH.
    They should have made this as a FULL bar across, not just that little latch… OR… done what every one else does… use bolts to tighten it down.
    AND… my XD9 Mod 2 SC only has ONE rail and because of the way they designed the piece inside (long rectangle tube) that holds the spring for the latch… I can’t push the UM3 back far enough to catch the one rail.

    Oh well…. $60 down the drain.

  10. I tried the Fab Defense USM on my Glock 17 Gen4. Because the front end of the slide is being curved up a little bit, I was not able to zero my Bushnell TRS. I guess, this problem will be the same with the UM-Tactical. Am I right? Or is there a solution for that problem?
    Best regards from Germany…

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