Optics and Sighting Systems

What is the best optic for my Glock 43x MOS

If you need an optic for your Glock 43X, I’m here to help. The Modular Optic System, or MOS, version of the G43X has a factory cut slide that accepts only micro-footprint sized optics using the RMSc-type base. Not every red dot sight (RDS) will fit.

Initially popularized by the Smith & Wesson Shield series, the RMSc footprint is now used for a range of guns including the SIG SAUER P365 series and the Springfield Armory Hellcat optics. The sights are more compact than normal pistol red dot sights and are necessary for slim guns like the G43X.

Red Dot Sight on Glock 43X MOS

I’ve thoroughly researched the use of reflex sights on pistols and have tested more than a few of the options on the market. To help you make a decision on which red dot might work best for your needs, I present my Glock 43X optics list.

These optics will also fit the Glock 48 MOS pistol. While I try to keep the list current, I recognize I may miss a new product release. So, feel free to leave information about anything not on the list in the comments section below.


Before I get into the details of each optic, here is a comparison table of the features and prices on the options currently available.

Riton Optics X3 TACTIX MPRDShield Sights RMScShield Sights SMScSIG SAUER Romeo ZeroSwampfox SentinelTrijicon RMRcc
Body Construction6061-T6 aluminumunknown type aluminumpolymerpolymer7075-T6 aluminum7075-T6 aluminum
Window Constructionmulti-coated glasspolymer with anti-reflection coatingpolymer with Quartz coating and glass optionspolymer with impact resistance coatingmulti-coated glassmulti-coated glass
Dot Size3 MOA4 and 8 MOA options4 and 8 MOA options3 and 6 MOA options3 MOA3.25 and 6.0 MOA options
Manual or Automaticmanualautomaticautomaticauto on, manual adjustmentsmanual and automatic optionsconstant on, manual adjustments
Levels of Illumination10unspecifiedunspecified8 daytime10 manual, continuous in automatic8
NV Compatibilityyes – 2 levelsyesyesnoyesyes – 2 levels
Weight0.6 oz0.57 oz0.57 oz0.4 oz0.62 oz1.0 oz
Battery Type1xCR20321xCR20321xCR20321xCR20321xCR20321xCR2032
Water Resistancestated 100% waterproofnonenonenoneIPx7 certifiedstated waterproof to 20 meters
Country of ManufactureChinaEnglandEnglandChinaChinaUSA
Warrantylifetime of optic, no paperwork7 years on electronics, infinite for all else7 years on electronics, infinite for all else5 years on electronics, infinite for all elsefull warranty for 50,000 rounds of live firelifetime
Best Online PriceClick HereClick HereClick HereClick HereClick HereClick Here

MSRP prices for the Shield Sights models are estimates based on a currency exchange and inclusion of the VAT imposed by the United Kingdom.

Riton Optics X3 TACTIX MPRD

Riton Optics offers a solidly built mini red dot optic for your slimline Glock pistol. Called the X3 TACTIX MPRD, this sight is made with a 6061-T6 aluminum body and a multi-coated lens. From a durability standpoint, only the Swampfox Sentinel (scroll down) beats it.

The X3 TACTIX MPRD is a fully manual optic with 10 red dot brightness levels. Levels one and two are night-vision compatible while the remaining brightness levels are compatible with the Mk1 eyeball in a range of lighting conditions. An auto-shutoff feature kicks in at 12 hours.

Riton X3 TACTIX MPRD Red Dot Optic

Riton claims a 99.5% light transmission rate with its high-density glass and multi-coatings. The lens coatings are said to reduce reflection, improve clarity in low light and resist scratching.

The company has a simple warranty: if it ever fails send it back and Riton Optics will send you a new one. You don’t need to have the product registered, you don’t need any paperwork and you don’t even need to be the original purchaser. The company’s goal is to have any return processed within 48 hours. It would be tough to beat that kind of service.

The suggested retail price on the optic is $299.99. The sight is relatively new, so you need to purchase it directly from Riton. As it makes its way into the market, I’m sure we will see discounts on this sight through the regular retailers.

Shield Sights Ltd

Shield Sights is the longest-running manufacturer of micro red dots for pistols like the Glock 43X. Currently, the company offers two basic models: the RMSc and the SMSc.

The models are similar but have some significant differences. Let’s take a look.


Built in England, the RMSc uses an aluminum body with a polymer lens to display a red aiming dot. Shield Sights does not list the type of aluminum it uses for the body.

RMSc for Glock 43X and Glock 48 pistol

Shield Sights uses an anti-reflection coating on the lens to reduce glare when aiming your G43X. Polymer lenses are used in a number of reflex sights and tend to keep manufacturing costs down. However, some people report the lenses are more susceptible to scratching.

You can purchase this sight with either a 4 MOA or 8 MOA dot. For me, I prefer the 4 MOA, but the 8 MOA really jumps out at you. For close-in defensive shooting, the larger dot is not a bad choice, so pick whatever you think will work best for you.

Shield does not identify how many levels of brightness the sight can employ. Rather, the dot automatically adjusts based on the lighting conditions.

Shield offers a 7-year warranty on the electronics in the RMSc and a lifetime warranty on the remaining components.

Shield RMSc on Glock pistol

As Shield is an English company, purchases direct from the company require a currency conversion from US dollars to British pounds. Further, purchases will incur a VAT or value-added tax. At the time of this writing, the suggested retail price of the sight is £300 before the VAT. Once the currency conversion and VAT are added, the price is about $472.98 plus overseas shipping.

If you prefer, you can order the sight here for only $430 with free shipping and returns.


Another Shield product, this unit has a similar appearance but a few new features as well. The most obvious change is that the SMSc uses a polymer body instead of aluminum.

Shield also gave the lens a rework. Now you can get the polymer lens with a special quartz hard coating on it for increased durability and scratch resistance. You can also have the polymer lens replaced entirely with a glass lens.

Shield Sights SMSc

As with the RMSc, the SMSc is a constant-on sight with an automatically adjusting brightness. When mounted on your Glock pistol, a sensor measures the ambient light and changes the red dot’s relative brightness.

The SMSc can be purchased with a 4 MOA or 8 MOA aiming dot. It enjoys the same 7-year/unlimited warranty that the RMSc has.

With the quartz-coated polymer lens, the MSRP with VAT for the SMSc is $346.85. A glass lens upgrade will cost an additional $126.13 for a total of $472.98. Coincidentally, that is the same price as the RMSc.

Alternatively, you can try to grab one from a US-based retailer. Right now, however, the only retailer that seems to be carrying them is Springfield Armory. The company’s asking price is $299, but they are out of stock with no expected restock date.

SIG SAUER Romeo Zero

If you weren’t already aware, SIG SAUER is now an optics manufacturer. The company makes everything from range finders to high power scopes. One of its more recent additions is the Romeo Zero RDS that fits the Glock 43X and other slimline pistols.

The Romeo Zero is manufactured with a polymer body and lens. This lends itself to being light – roughly 0.4 ounces according to the company’s specifications.

SIG Romeo Zero RDS for the Glock Slimline Pistols

For durability, I much prefer a 6061 or 7075 aluminum body. However, polymer has proven to be a durable material for gun parts. Likewise, I prefer a glass lens. Polymer, however, is a proven material for optics so you should be fine with this sight unless you abuse it.

SIG uses a motion activation system to turn the red dot on. The system seems to work well, and I have no issue with relying on it.

The dot brightness is manually controlled. With the Romeo Zero, you get 8 manually adjustable brightness levels. There are two available models: one with a 3 MOA dot and a second with a larger 6 MOA dot.

One of the highlights of this sight is its pricetag: $219. Buying it online drops the total cost below $200 with free shipping. That is the best priced deal on this list by a fairly wide margin.

Special Note

Reader Mike W. sent me an email about the Romeo Zero’s compatibility with the G43X MOS. He said that the mounting screws that are included with the sight are too long for the Glock pistol. This mirrors the problem that I discovered when trying to mount the Romeo Zero to the Springfield Armory Hellcat.

I’m trying to track down a drop-in replacement screw set. It has been suggested to me that these M4-0.70x8mm flat head screws are a good replacement, but I have not confirmed this yet.

If you are running a Romeo Zero on your Glock 43X MOS, can you let us know what modifications or alternative screws you had to use?

Swampfox Sentinel

Currently, the Swampfox Sentinel is my favorite red dot sight for pistols with the RMSc-type base.

The Sentinel is tough and built to take a beating. Swampfox machines the body from 7075-T6 aluminum – the same hardened metal used in forged AR lowers.

Swampfox Sentinel RDS

For the lens, Swampfox uses an optical glass that has been multi-coated to give it resistance to fogging, water, mud and scratches.

Further, the Sentinel is the only sight on this list with an IP rating: a standardized rating system for measuring water and dust intrusion into electronics and other devices.

The Sentinel is rated at IPX7. That means it is submersible to 1 meter for up to 30 minutes. None of the other optics offers anything close to this.

Swampfox offers the RDS in two models: one is completely manual with 10 brightness levels while the other is a constant on version with an infinitely adjustable, automatic brightness level. I own the full-auto version, and it works just as advertised.

The photosensor samples ambient lighting and near-instantly adjusts the 3 MOA red dot. In actual use, I’ve found it works perfectly.

Side view of Sentinel RDS for Glock 43X

Swampfox offers a 50k round warranty on the Sentinel. In other words, if you have any problems with it during the first 50,000 rounds of live fire, they will make it right. If you shoot 1,000 rounds/year, you will have the company’s backing for the next 50 years. I bet, however, the company would be willing to step up for any defect in its manufacturing regardless of round count.

Due to the incredible popularity of the Sentinel, the sights sell out quickly. However, they are available at a discount here.

Trijicon RMRcc

Trijicon’s RMR line of red dot sights is highly regarded for their durability and performance. For the micro-compact pistols, the company introduced the RMRcc which is both narrower and lighter, but just as rugged as the original.

Trijicon RMRcc for Glock 43X MOS

The RMRcc uses a unique mount that deviates from the rest of the industry that standardized on the RMSc-type mount. But, Trijicon does offer a wide range of mounting plates.

Mounting Plate Note

Earlier reports that Trijicon was making a plate for the Glock 43X MOS were incorrect. Trijicon currently recommends people purchase a third-party mounting plate from C&H Precision. These plates are $69.99 each and are in production now.

The mount is not the only thing that makes the RMRcc unique on this list. It is also the only optic that is 100% made in the USA – from design to machining to assembly, everything is done with American citizens in facilities located in the continental United States.

As with the Swampfox option above, Trijicon uses a tough 7075-T6 aluminum housing for its red dot sight. Your Glock 43X is designed to take a beating, and Trijicon designed the RMRcc to perform in the roughest of conditions. The company states that the optics have been temperature tested, drop tested, vibration tested and water intrusion tested. While the company does not provide an IP-rating for the optic, it states the RMRcc is good to 20 meters underwater.

You don’t get made in the USA quality for free. This optic is easily the most expensive available for the Glock 43X MOS. However, don’t stress over the “suggested” retail price of $699. You can get one for a lot less through our affiliate link here. And for that money, you get what may be the toughest red dot sight available for the Glock 43X MOS.

Wrap Up

All of the sights on this list will work for your slimline Glock 43, 43X, and 48. However, two stand out to me.

Glock 43X Optics

For the absolute best sight, the Trijicon RMRcc is the only choice. They are made in the USA and are ruggedized for combat duty.

If you are looking for near-Trijicon performance without as large a bite in your wallet, the Swampfox Sentinel is the way to go. Even at full MSRP, the fully-automatic sight is less than $300 and you get 7075-T6 construction with IPX7 water immersion capabilities. This is the optic I am currently running on my carry gun.

However, if you are on a budget, the SIG Romeo Zero is tough to beat. This link will get you the sight for less than $200 with free shipping. While the build quality isn’t quite as good as the Sentinel, the Romeo Zero is a full $100 cheaper.

Last update: May 19, 2021.

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By Richard Johnson

Richard Johnson is a gun writer, amateur historian and - most importantly - a dad. He's done a lot of silly things in his life, but quitting police work to follow his passion of writing about guns was one of the smartest things he ever did. He founded this site and continues to manage its operation.

55 replies on “What is the best optic for my Glock 43x MOS”

Awesome article. I love your posts.

Alright, so is it possible to mount an RMR to this thing? I realize the RMR is Much wider than the slide but i still want it.

Thanks for your kind words Stephen.

You can mount the RMR to the G43x and other RMSc-type cuts. You need to get an adapter plate. Without digging too deeply, I see Brownells has one for about $85. However, MapleLeaf Firearms in Celina, TX has a plate for $40. I’ve never tested it or know anything about the company but for the price difference, I think I’d give them a shot.

I hope that helps!

If you try it out (or try something different), would you leave a comment about how it worked out for anyone else needing the same thing?


Hi Joe_K,

Thanks for the feedback. Just so we are on the same page, Stephen was asking about the original RMR (not the newly released RMRcc that was announced after he asked.) If I’m reading the Maple Leaf site correctly, the plate is designed to adapt the full-size RMR to the RMSc pattern mount.

Do I have it right or have I gone off the rails here? I don’t want to make bad recommendations to people.


Hi Matt,

Holosun said those optics are not yet available. I just double-checked the company’s website and it still says “Coming soon”. Do you have different information?


Hi Eddi,

According to Holosun, the sights will be “compatible with some standard mounting solutions currently available.”

I’ve not seen an official statement from the company on the pattern/size matching the RMSc mount. Other people online are reporting that it will, so I am hopeful. If it does not, I expect the company will offer an adaptor plate, though that does slightly increase the size and weight of the package.


Hi Eddi,

I spoke with a rep for Holosun today. They have no ETA on when the sights might be available. Not even a “by the end of the year.” So, it might be a while.

Also, I confirmed that the K models will use a proprietary footprint. That means adaptor plates will be required.

I hope this helps.


The 507k does use the RMSc screw pattern, but not the two corner indexing lugs associated with it. So if a pistol has them, they have to be filed down flat. Other than that, a 507k can go on any pistol with a Shield footprint.
Trijicon basically forced Holosun to go back to it’s small button set up. Once back on the market, they will go right back to being a thorn in Trijicon’s side. All the reliability and durability for half the price.

Thanks for the clarification on the lugs. Holosun definitely brings a lot of competition to the market, which is a good thing. Now that the Trijicon settlement is in, maybe they will start shipping these soon. I don’t know how many people are willing to grind the lugs off though. That seems to limit who will want to buy them. I wonder what I’m missing on that design decision.


An rmsc mount for the 507k requires total takedown of the back posts and about halfway on the front two if that helps at all.

I generally lean toward Surefire and Streamlight products based on my experience with them. However, the Olight weaponlights are surprisingly good. I haven’t tested it on the 43X, but the PL-2 Valkyrie might be a good match. If you are looking for something very compact, I am testing a PL-Mini 2 Valkyrie right now on a Hellcat. It is very compact with an easy charger and a respectable amount of light. Both are less than $100.


Hi John,

Yes, it is a SureFire. However, I do not know which model it is yet. The image was provided to my by Glock and they referred my to SureFire for information on it. I have not gotten a response from SureFire yet, but I will let you know when I have more information to share. I didn’t see anything in the company’s catalog that seemed to be an exact match, so I wonder if it is a new product that just hasn’t been announced yet.


The Olight mini PL-2 will not mount on a 43XMOS. The rail is too thin so it wobbles bad and doesn’t stay secure. I know because I have both.

Hi John,

Thanks for the note. The Romeo Zero’s last substantial transformation (last major assembly action) happened in the US which allows SIG SAUER to claim “Assembled in USA.” Sadly, it is not made in America. If it was, the company would just say that.

Following the FTC guidelines, SIG cannot claim that it is made in the USA since either all or a substantial number of its parts are made overseas.

Refer also to:

Complying with the Made in USA Standard
Enforcement Policy Statement on U.S. Origin Claims

I hope this helps.


The ROMEOZero is assembled in Wilsonville, Oregon. Rumors abound in the optics industry of companies that simply put a battery in a red dot, or put a scope inside of a box and claim “Assembled in USA”. But I can assure you that every major component of the ROMEOZero is physically put together here in the US.

Hi John,


I’ve correctly listed where the Romeo Zero is manufactured. Final assembly and where the parts are made are completely different things as you well know. For those that are not aware, feel free to read the FTC guidance in the links above.

If you could have claimed made in the USA, you would have.

I’ve not talked about rumors on any optics and unless you are trying to confuse potential buyers, I’m unsure why you are bringing that up. Any company that does as you state the rumors claim would appear to be committing fraud and subject to FTC enforcement.

Finally, so readers have a full understanding of who is playing white knight for SIG SAUER, I’ll just post your own words:

John Nichols - SIG SAUER

– Richard

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