Parts made for a Glock 19 won't fit a 43X or 48, so every pick below is a Slimline part listed for these two pistols, with prices from the merchants we track.
Best Glock 43X and 48 upgrades
- Best upgrade overall: Glock 15 round magazine (79269), about $30 when it's in stock.
- Best if you already run S15s: Shield Arms S15 Gen 3, about $38, plus Shield's steel catch from about $11.
- Best direct mount red dot: Shield RMSc Glass Edition, from about $265.
- Best K footprint red dot: Holosun 507K, from about $320.
- Best weapon light: Streamlight TLR-7 X Sub, from about $140.
- Best trigger kit: Apex Slim Frame Action Enhancement kit, about $112.
- Best night sights for a pistol without MOS: Trijicon HD XR small frame set, from about $135.
Best upgrade overall: Glock 15 round magazine (79269)
A 15 round magazine in the same footprint as the flush 10 rounder is the biggest change you can make to a 43X or 48. Glock's own metal double stack version was built to run on the catch your pistol already has, so nothing else needs to change.
What we like
- Glock says it put a radius in the catch recess, so you keep the factory polymer magazine catch you already have.
- You get five more rounds in the same footprint, so the grip and the holster you carry today stay the same.
- It's built for the same G43X and G48 frame as older pistols, which makes an older gun the case Glock designed for.
Watch out for
- Nobody we can link has tested it in a Shield steel catch, and Gold Trigger calls that pair incompatible without citing a test.
- Where your state caps magazines at 10 rounds, you can't buy it, so check the limit before you order.
Best if you already run S15s: Shield Arms S15 Gen 3
Shield Arms sold a 15 round Slimline magazine before Glock did, and the Gen 3 S15 is in stock at three merchants we track for about $38 to $41. It's a steel magazine, and Shield builds the whole system around its own steel catch.
What we like
- You can buy it today, while Glock's 79269 sits out of stock at the merchant we track.
- Shield's steel catch runs from about $11, so switching the whole pistol over stays cheap.
Watch out for
- Shield says the S15 needs its steel magazine catch, so you'll swap a part before the first magazine goes in.
- Shield warns that Glock's plastic magazines may not drop free from the steel catch, so plan on one system per pistol.
Best direct mount red dot: Shield RMSc Glass Edition
The 43X MOS and 48 MOS slides are cut for the Shield RMSc pattern, and Glock names the RMSc as the kind of optic the cut takes. This listing is the Glass Edition with a 4 MOA dot, and it sits straight on the slide's four posts.
What we like
- Freedom Gorilla lists the RMSc as a direct fit on the 43X and 48 MOS, so you don't buy an adapter plate.
- Glock says you can see the standard sights through the lens on the MOS pistols, so you don't need taller sights.
Watch out for
- Rail and railless slides have no optic cut, so you'd have to mill the slide or replace it before this dot goes on.
- Prices run from about $265 to about $380 across the merchants we track, so the cheapest listing saves real money.
Best K footprint red dot: Holosun 507K
The 507K is Holosun's small K footprint dot, and this listing is the green dot version with a 2 MOA dot. Glock began moving the Slimline slides to a MOS-K cut in late 2025, and a K footprint dot mounts direct on those.
What we like
- On a slide marked MOSK near the end of the item number on the case, Night Fision says a K dot mounts with no plate.
- It's in stock at a long list of merchants, with prices starting around $320 when we last updated this page.
Watch out for
- An older MOS slide needs a thin plate such as C&H's GLX-HOLOk, because the K footprint only recesses the two front posts.
- The other route on an older slide is a C&H milling job for a direct K mount, and that means shipping your slide away.
Best weapon light: Streamlight TLR-7 X Sub
Streamlight built the TLR-7 Sub for the slim rail on the 43X and 48, and the newer TLR-7 X Sub comes in a version for the same frames. This listing is that version, and several merchants have it in stock from about $140.
What we like
- Streamlight's page lists the 43X MOS, 48 MOS, 43X Rail and 48 Rail, so it covers every railed Slimline Glock sells today.
- It's in stock at several merchants we track, with the lowest listings around $140.
Watch out for
- An original railless 43X or 48 has nothing to clamp it to, so this pick only works on a Rail or MOS pistol.
- The TLR-7 X Sub is sold in versions for different pistols, so make sure the listing names the 43X and 48.
- A light means a light bearing holster, and the holster you carry now probably won't take it.
Best trigger kit: Apex Slim Frame Action Enhancement kit
Slimline fire control parts are their own family, and Apex sells its Action Enhancement kit in a slim frame version listed for the 43, 43X and 48. One kit covers either pistol, which keeps the order simple.
What we like
- The MidwayUSA listing names all three Slimline pistols, so you don't need a different kit for a 43X and a 48.
Watch out for
- A kit made for a 19 or a Gen5 won't fit, so order the slim frame version and check the listing before you pay.
- At about $112 it costs more than Overwatch's DAT kit, which runs about $73 at the merchant we track.
Best night sights for a pistol without MOS: Trijicon HD XR
Glock lists these pistols with polymer, steel or night sights, and on a carry gun the polymer set is the first thing we'd change. Trijicon's HD XR small frame set is listed for the 42, 43, 43X, 43E and 48.
What we like
- One set covers the whole small frame family, so the same part fits a 43X or a 48.
- It's in stock at four merchants we track, from about $135 at the low end.
Watch out for
- Trijicon's page for its HD XR small frame set says it excludes MOS models, so check the part number before you order for an MOS.
- On an MOS pistol with a direct mount dot, Glock says the standard sights already show through the lens.
Why Glock 19 parts don't fit a 43X or 48
People buy a 43X or 48 and assume that because it says Glock on the slide, Glock parts will fit it. They won't, because the Slimline is a separate parts ecosystem, and makers sell Slimline versions of magazines, sights, slides and trigger kits under their own part numbers.
The 43X and the 48 share almost everything with each other: the frame, the grip, the magazines and the trigger parts. They differ in slide and barrel length. The 48 MOS's barrel is 0.76 in longer, and Glock lists it 2.05 oz heavier than the 43X MOS with an empty magazine.
Glock US spec pages read 2026-09-27; capacity from Glock, April 17, 2026
| Metric | Value |
|---|---|
| Width, 43X and 48 (Glock 19 V: 1.34 in) | 1.10 in |
| Glock 48 vs Glock 19 V, length x height | Same 7.28 x 5.04 in |
| 43X MOS, empty mag (Glock 19 V: 23.63 oz) | 18.55 oz |
| Glock's announced standard magazine, April 17, 2026 | 15 rounds |
Glock 43X vs 48 vs 43 vs 19, to scale
We drew all four pistols from Glock's own spec pages. The 43X is the solid outline, and you can switch the others on and off to lay them over it.
Glock 43X vs 48 vs 43 vs 19 V, to scale
Glock's spec pages, read 2026-09-27. Weights with the 10 round magazine Glock still lists. On April 17, 2026 Glock announced a 15 round metal magazine and said the 43X and 48 will come standard with it.
One square is one inch. Aligned at the slide rear and sight top, the way the guns sit in your hand.
| Pistol | Length (in) | Slide (in) | Height (in) | Width (in) | Weight (oz) | Barrel (in) |
|---|---|---|---|---|---|---|
| Glock 43X | 6.5 | 6.06 | 5.04 | 1.1 | 18.55 | 3.41 |
| Glock 48 | 7.28 | 6.85 | 5.04 | 1.1 | 20.6 | 4.17 |
| Glock 43 | 6.26 | 6.06 | 4.25 | 1.06 | 17.99 | 3.41 |
| Glock 19 V | 7.28 | 6.85 | 5.04 | 1.34 | 23.63 | 4.02 |
The 48 has a Glock 19 V's outline, since both are 7.28 in long and 5.04 in tall. Glock lists the 48 MOS 0.24 in narrower overall than a 19 V, 0.13 in narrower at the slide, and 3.03 oz lighter with an empty magazine.
The 43X is just as tall at 5.04 in and 0.78 in shorter overall. The 43 is the odd one out, a single stack six rounder only 4.25 in tall, and its magazines don't fit a 43X or 48.
| Model | Caliber | Length | Height | Width | Barrel | Weight (empty mag) | Capacity |
|---|---|---|---|---|---|---|---|
| Glock 43 | 9mm | 6.26 in | 4.25 in | 1.06 in | 3.41 in | 17.99 oz | 6 |
| Glock 43X Rail | 9mm | 6.50 in | 5.04 in | 1.10 in | 3.41 in | 18.70 oz | 10 |
| Glock 43X MOS | 9mm | 6.50 in | 5.04 in | 1.10 in | 3.41 in | 18.55 oz | 10 |
| Glock 48 Rail | 9mm | 7.28 in | 5.04 in | 1.10 in | 4.17 in | 20.74 oz | 10 |
| Glock 48 MOS | 9mm | 7.28 in | 5.04 in | 1.10 in | 4.17 in | 20.60 oz | 10 |
| Glock 19 V | 9mm | 7.28 in | 5.04 in | 1.34 in | 4.02 in | 23.63 oz | 15 |
Glock's pages still list 10 rounds for the 43X and 48, and their weights are with that magazine. Glock has said the two pistols will come standard with its new 15 round magazine, but it hasn't given a date for that change.
Glock 43X upgrades list: what fits which Slimline
There are more Slimline variants than most parts listings admit. Glock introduced the 43X and 48 in July 2019 with no rail, then added MOS versions with an optic cut and a slim accessory rail on August 24, 2020. Today Glock US lists only the Rail and MOS pistols.
Pick yours in the chart below to see what fits it. Where nobody we can link has tested a pairing, the row says unknown rather than guessing.
What fits your Slimline
From Glock, Shield Arms, Streamlight, maker and retailer listings, checked 2026-09-27
8 of 25 fit the Glock 43X Rail outright, and 3 more fit with a catch.
- Glock 15 round magazine (79269)Fits. Glock's own. Glock says it runs on the factory polymer catch.
- Shield Arms S15, 15 roundsFits, with a catch. Fits, but Shield Arms requires its steel magazine catch.
- Glock 10 round 43X/48 magazineFits.
- Glock 43 six round magazineWon't fit. Glock lists the 43 as a single stack six rounder. It's a different magazine.
- Glock 19 magazineWon't fit. Built for the wider double stack frame; these are 1.10 in.
- Glock 15 rounder with a Shield steel catch fittedUnconfirmed. Glock built it for the polymer catch. Shield's guidance doesn't mention it. Retailer Gold Trigger calls the pair incompatible but cites no test.
- Glock 43X slide or upperFits.
- Complete Glock 48 upperUnconfirmed. Glock says the 43X and 48 share the same size frame but doesn't list a slide swap, and we found no source that tests one.
- Glock 43 slideFits. Aftermarket slides are sold for the 43 and 43X together.
- RMSc cut aftermarket 43X slide (Zaffiri ZPS.2)Fits.
- Glock 19 slideWon't fit. A 19 V slide is 1.00 in wide, for a standard frame. These slides are 0.87 in.
- Shield RMSc footprint dot (RMSc, Vortex Defender CCW)Won't fit. No optic cut; mill or replace the slide.
- Holosun 507K, 407KWon't fit. No optic cut.
- Holosun EPS CarryWon't fit. No optic cut.
- Trijicon RMRccWon't fit. No optic cut.
- RMR, 507C or ACRO on a Slimline plate (C&H, Forward Controls Design)Won't fit. No optic cut.
- Full size Glock MOS plateWon't fit. Cut for the standard slide. C&H's standard MOS plate lists no 43X or 48.
- Factory height iron sights with a direct mount dotWon't fit. No dot to look through.
- Streamlight TLR-7 Sub or TLR-7 X Sub (slim rail version)Fits.
- Light bearing holster for TLR-7 SubFits, with a catch. Check the listing names the Rail frame.
- Holster cut for a 43X (closed bottom)Fits, with a catch. Check the listing names your frame.
- Slimline trigger kit (Apex Slim Frame AEK, Overwatch DAT)Fits. Sold for the 43, 43X and 48.
- Glock 19 or Gen5 trigger kitWon't fit. Standard frame parts.
- Glock 43X barrel, 3.41 inFits.
- Glock 48 barrel, 4.17 inWon't fit. Too long for the 43X slide.
| Part | Glock 43X Rail | Glock 43X MOS | Glock 48 Rail | Glock 48 MOS | Glock 43X or 48 without a rail |
|---|---|---|---|---|---|
| Magazines: Glock 15 round magazine (79269) | Fits. Glock's own. Glock says it runs on the factory polymer catch. | Fits. Glock's own. Glock says it runs on the factory polymer catch. | Fits. Glock's own. Glock says it runs on the factory polymer catch. | Fits. Glock's own. Glock says it runs on the factory polymer catch. | Fits. Same G43X and G48 frame. Glock says it runs on the standard catch. |
| Magazines: Shield Arms S15, 15 rounds | Fits, with a catch. Fits, but Shield Arms requires its steel magazine catch. | Fits, with a catch. Fits, but Shield Arms requires its steel magazine catch. | Fits, with a catch. Fits, but Shield Arms requires its steel magazine catch. | Fits, with a catch. Fits, but Shield Arms requires its steel magazine catch. | Fits, with a catch. Fits, but Shield Arms requires its steel magazine catch. |
| Magazines: Glock 10 round 43X/48 magazine | Fits | Fits | Fits | Fits | Fits |
| Magazines: Glock 43 six round magazine | Does not fit. Glock lists the 43 as a single stack six rounder. It's a different magazine. | Does not fit. Glock lists the 43 as a single stack six rounder. It's a different magazine. | Does not fit. Glock lists the 43 as a single stack six rounder. It's a different magazine. | Does not fit. Glock lists the 43 as a single stack six rounder. It's a different magazine. | Does not fit. Glock lists the 43 as a single stack six rounder. It's a different magazine. |
| Magazines: Glock 19 magazine | Does not fit. Built for the wider double stack frame; these are 1.10 in. | Does not fit. Built for the wider double stack frame; these are 1.10 in. | Does not fit. Built for the wider double stack frame; these are 1.10 in. | Does not fit. Built for the wider double stack frame; these are 1.10 in. | Does not fit. Built for the wider double stack frame; these are 1.10 in. |
| Magazines: Glock 15 rounder with a Shield steel catch fitted | Unconfirmed. Glock built it for the polymer catch. Shield's guidance doesn't mention it. Retailer Gold Trigger calls the pair incompatible but cites no test. | Unconfirmed. Glock built it for the polymer catch. Shield's guidance doesn't mention it. Retailer Gold Trigger calls the pair incompatible but cites no test. | Unconfirmed. Glock built it for the polymer catch. Shield's guidance doesn't mention it. Retailer Gold Trigger calls the pair incompatible but cites no test. | Unconfirmed. Glock built it for the polymer catch. Shield's guidance doesn't mention it. Retailer Gold Trigger calls the pair incompatible but cites no test. | Unconfirmed. Glock built it for the polymer catch. Shield's guidance doesn't mention it. Retailer Gold Trigger calls the pair incompatible but cites no test. |
| Slides and uppers: Glock 43X slide or upper | Fits | Fits | Unconfirmed. Glock says the 43X and 48 share the same size frame but doesn't list a slide swap, and we found no source that tests one. | Unconfirmed. Glock says the 43X and 48 share the same size frame but doesn't list a slide swap, and we found no source that tests one. | Fits, with a catch. On a 43X frame. Nobody we found has tested it on a 48's. |
| Slides and uppers: Complete Glock 48 upper | Unconfirmed. Glock says the 43X and 48 share the same size frame but doesn't list a slide swap, and we found no source that tests one. | Unconfirmed. Glock says the 43X and 48 share the same size frame but doesn't list a slide swap, and we found no source that tests one. | Fits | Fits | Fits, with a catch. On a 48 frame. Nobody we found has tested it on a 43X's. |
| Slides and uppers: Glock 43 slide | Fits. Aftermarket slides are sold for the 43 and 43X together. | Fits. Aftermarket slides are sold for the 43 and 43X together. | Unconfirmed. Listings name the 43 and 43X, not the 48. | Unconfirmed. Listings name the 43 and 43X, not the 48. | Fits, with a catch. Listings name the 43 and 43X, not the 48. |
| Slides and uppers: RMSc cut aftermarket 43X slide (Zaffiri ZPS.2) | Fits | Fits | Unconfirmed. Zaffiri's listing names the 43 and 43X, not the 48. | Unconfirmed. Zaffiri's listing names the 43 and 43X, not the 48. | Fits, with a catch. Zaffiri names the 43 and 43X, not the 48. |
| Slides and uppers: Glock 19 slide | Does not fit. A 19 V slide is 1.00 in wide, for a standard frame. These slides are 0.87 in. | Does not fit. A 19 V slide is 1.00 in wide, for a standard frame. These slides are 0.87 in. | Does not fit. A 19 V slide is 1.00 in wide, for a standard frame. These slides are 0.87 in. | Does not fit. A 19 V slide is 1.00 in wide, for a standard frame. These slides are 0.87 in. | Does not fit. A 19 V slide is 1.00 in wide, for a standard frame. These slides are 0.87 in. |
| Optics: Shield RMSc footprint dot (RMSc, Vortex Defender CCW) | Does not fit. No optic cut; mill or replace the slide. | Fits. Direct to the slide's four posts. | Does not fit. No optic cut; mill or replace the slide. | Fits. Direct to the slide's four posts. | Does not fit. No optic cut; mill or replace the slide. |
| Optics: Holosun 507K, 407K | Does not fit. No optic cut. | Fits, with a catch. Needs a thin plate, such as C&H's GLX-HOLOk, to clear the rear posts. A slide marked MOSK takes it direct. | Does not fit. No optic cut. | Fits, with a catch. Needs a thin plate, such as C&H's GLX-HOLOk, to clear the rear posts. A slide marked MOSK takes it direct. | Does not fit. No optic cut. |
| Optics: Holosun EPS Carry | Does not fit. No optic cut. | Fits, with a catch. Mounts with the RMSc plate Holosun ships in the box, which clears the rear posts. | Does not fit. No optic cut. | Fits, with a catch. Mounts with the RMSc plate Holosun ships in the box, which clears the rear posts. | Does not fit. No optic cut. |
| Optics: Trijicon RMRcc | Does not fit. No optic cut. | Fits, with a catch. Needs a 43X/48 MOS plate, from Trijicon or C&H. | Does not fit. No optic cut. | Fits, with a catch. Needs a 43X/48 MOS plate, from Trijicon or C&H. | Does not fit. No optic cut. |
| Optics: RMR, 507C or ACRO on a Slimline plate (C&H, Forward Controls Design) | Does not fit. No optic cut. | Fits, with a catch. Plates made for this cut exist. An RMR is 1.1 in wide on a 0.87 in slide. | Does not fit. No optic cut. | Fits, with a catch. Plates made for this cut exist. An RMR is 1.1 in wide on a 0.87 in slide. | Does not fit. No optic cut. |
| Optics: Full size Glock MOS plate | Does not fit. Cut for the standard slide. C&H's standard MOS plate lists no 43X or 48. | Does not fit. Cut for the standard slide. C&H's standard MOS plate lists no 43X or 48. | Does not fit. Cut for the standard slide. C&H's standard MOS plate lists no 43X or 48. | Does not fit. Cut for the standard slide. C&H's standard MOS plate lists no 43X or 48. | Does not fit. Cut for the standard slide. C&H's standard MOS plate lists no 43X or 48. |
| Optics: Factory height iron sights with a direct mount dot | Does not fit. No dot to look through. | Fits. Glock says the standard sights show through the lens. | Does not fit. No dot to look through. | Fits. Glock says the standard sights show through the lens. | Does not fit. No dot to look through. |
| Holsters and lights: Streamlight TLR-7 Sub or TLR-7 X Sub (slim rail version) | Fits | Fits | Fits | Fits | Does not fit. No rail. |
| Holsters and lights: Light bearing holster for TLR-7 Sub | Fits, with a catch. Check the listing names the Rail frame. | Fits | Fits, with a catch. Check the listing names the Rail frame. | Fits | Does not fit. No rail, so no light. |
| Holsters and lights: Holster cut for a 43X (closed bottom) | Fits, with a catch. Check the listing names your frame. | Fits, with a catch. Check the listing names the MOS and your dot. | Does not fit. The 48 slide is 0.79 in longer. | Does not fit. The 48 slide is 0.79 in longer. | Fits, with a catch. Check the listing names the plain 43X. |
| Triggers: Slimline trigger kit (Apex Slim Frame AEK, Overwatch DAT) | Fits. Sold for the 43, 43X and 48. | Fits. Sold for the 43, 43X and 48. | Fits. Sold for the 43, 43X and 48. | Fits. Sold for the 43, 43X and 48. | Fits. Sold for the 43, 43X and 48. |
| Triggers: Glock 19 or Gen5 trigger kit | Does not fit. Standard frame parts. | Does not fit. Standard frame parts. | Does not fit. Standard frame parts. | Does not fit. Standard frame parts. | Does not fit. Standard frame parts. |
| Barrels: Glock 43X barrel, 3.41 in | Fits | Fits | Does not fit. Too short for the 48 slide. | Does not fit. Too short for the 48 slide. | Fits, with a catch. Only in a 43X. |
| Barrels: Glock 48 barrel, 4.17 in | Does not fit. Too long for the 43X slide. | Does not fit. Too long for the 43X slide. | Fits | Fits | Fits, with a catch. Only in a 48. |
Glock says the 43X and 48 share the same size frame, but it doesn't list a slide swap between them, and we haven't found anyone who has tested one. Nothing from a 19 crosses over, because a 19 V slide is 1.00 in wide against 0.87 in on these pistols.
Out of stock
The Glock 43X 15 round magazine is the upgrade that changes the gun
If your 43X or 48 came with the flush 10 round magazine, a 15 round magazine in the same footprint gives you five more rounds. The pistol doesn't get any bigger, so you keep the same holster and the same grip.
On April 17, 2026, Glock announced a 15 round metal double stack magazine for the 43X and 48, due at dealers in May 2026. It said both pistols will come standard with it, but its spec pages still list the 10 rounder, and retailers sell the new magazine as part 79269.
You don't need to touch the magazine catch for Glock's version. Glock says it put a radius in the catch recess so owners can keep the standard catch, and it's built for the same G43X and G48 frame as older pistols.
Shield Arms' S15 got there first, and it plays by different rules. Shield says the S15 needs its steel magazine catch, recommends steel on steel and plastic on plastic, and warns that Glock's plastic magazines may not drop free from the steel catch.
That retailer copy covers Shield's steel magazines and Glock's plastic ones, and it doesn't mention Glock's metal 15 rounder. Gold Trigger, a retailer, says the 79269 isn't compatible with Shield's steel release, but it doesn't say how it knows, and we haven't found anyone who has tested the pair.
Pick one system and stay with it. Glock built its magazine for the polymer catch, so if you're moving from S15s to Glock magazines, put the polymer catch back in first.
Which 15 round setup is yours?
Scored on Glock's and Shield Arms' own fit rules. A tie goes to Glock's magazine.
- 1. Does your state cap magazines at 10 rounds?
- 2. Do you already own Shield S15 magazines?
- 3. Which magazine catch is in your pistol now?
Answer any question and the pick updates as you go.
| Question | Answer | Points toward |
|---|---|---|
| Does your state cap magazines at 10 rounds? | Yes | Stay at 10. Where the cap is 10, the 10 round magazine is the one you can buy. |
| Does your state cap magazines at 10 rounds? | No | |
| Does your state cap magazines at 10 rounds? | Not sure | Stay at 10. Check your state's limit before you order. Until then the 10 rounder is the safe pick. |
| Do you already own Shield S15 magazines? | Yes | Shield S15 with steel catch. You already own S15s, and Shield says they want its steel catch. |
| Do you already own Shield S15 magazines? | No | Glock 15 round (79269). Starting fresh, Glock's magazine needs no other part. |
| Which magazine catch is in your pistol now? | The factory polymer catch | Glock 15 round (79269). Glock built its 15 rounder to run on the factory polymer catch. |
| Which magazine catch is in your pistol now? | A Shield Arms steel catch | Shield S15 with steel catch. Shield's steel catch is built for its steel S15. Glock built its own 15 rounder for the factory polymer catch. |
| Which magazine catch is in your pistol now? | I don't know | |
| Result | Glock 15 round (79269) | Glock's own magazine on the factory polymer catch. Nothing else to fit. |
| Result | Shield S15 with steel catch | Shield's steel magazine on Shield's steel catch. Shield says Glock's plastic mags may not drop free from it. |
| Result | Stay at 10 | Glock's 10 round magazine. The one you can buy where the cap is 10. |
Glock 43X and 48 sights: buy the small frame set
Sight makers sell separate sets for Glock's small frames, so a set for a 19 won't fit. Buy sights listed for your exact model, and on an MOS pistol read the fine print, because some small frame sets exclude MOS slides.
We'd rather have a bright front and a plain rear than three matching dots, since you're paying for front sight contrast. XS's DXW2 Big Dot set is another small frame option listed for the 42, 43, 43X and 48.
Optics: the Glock 43X MOS red dot footprint
A Slimline slide is 0.87 in wide, and that limits what sits on it. A Trijicon RMR is 1.1 in wide, so a full size dot hangs over both sides, and these pistols want a small footprint micro optic instead.
The 43X MOS and 48 MOS cut is the Shield RMSc pattern, which Glock calls a non standard MOS footprint. The pistol ships with no adapter plates, and Glock's full size MOS plates don't fit. C&H Precision's fit list for its standard Glock MOS plate runs from the G17 to the G47, with no 43X or 48 on it.
For a direct mount red dot on a 43X MOS, start with the Shield RMSc or the Vortex Defender CCW. Freedom Gorilla, a plate and optics retailer, lists both as direct fits on the slide's four posts.
The Holosun 507K and 407K don't drop straight onto most MOS slides. The K footprint has recesses for the two front posts only, so it needs a thin plate such as C&H's GLX-HOLOk to clear the rear ones. C&H also mills factory slides to take the K series direct.
The Holosun EPS Carry brings its own plate. Optics Force, an optics retailer, says it ships with an RMSc footprint plate and names the 43X and 48 MOS as slides that need it. The plate clears their rear posts, and the optic's own screws pass through it.
Glock has started changing the cut itself. Night Fision, a night sight maker, says Glock began moving the 43, 43X and 48 to a MOS-K cut in late 2025, and a K footprint dot mounts direct on it. Look for MOSK near the end of the item number on the case, and Freedom Gorilla lists the Coyote 43X MOS as one of them.
The Trijicon RMRcc needs a 43X/48 MOS plate from Trijicon or C&H. Trijicon's page for its plate says it doesn't fit what it calls the new Glock 48 MOS Gen 6, so check the listing against your slide before you order.
Plates for bigger optics exist too. C&H makes one for the RMR, SRO and Holosun 507C, and Forward Controls Design makes one for the Aimpoint ACRO, but expect any of those optics to sit wider than the slide.
Rail and railless slides have no cut. Milling a slide this thin is a job for a shop you trust, or you can swap to an RMSc cut aftermarket slide like Zaffiri's ZPS.2 for the 43 and 43X. Our red dot plate guide covers plates in more depth.
Glock 43X and 48 triggers
Apex's Action Enhancement kit and Overwatch's DAT are both sold for the 43, 43X and 48 together, so buy the Slimline version rather than the one for a 19.
The same logic applies as on any Glock. A flat faced shoe changes leverage and perceived weight, while the connector and springs change actual weight, and on a carry gun you want a cleaner break rather than a lighter pull. Our Glock trigger guide covers the whole system.
The Slimline's light weight adds one more thing to weigh. It moves more under recoil, and we think a very light trigger on a gun you're gripping hard is a poorer trade here than on a full size pistol.
Recoil system
Glock lists the 43X MOS at 18.55 oz with an empty magazine, against 23.63 oz for a 19 V, and less mass means the same cartridge moves it more.
Options run from a factory replacement spring to a stainless guide rod assembly like Rival Arms' below. Whichever you run, replace the spring on a schedule rather than waiting for it to fail.
Barrel
Glock's page for the 48 MOS says it carries the match grade Glock Marksman Barrel, so we wouldn't swap it for accuracy on a carry gun.
Threading is the real reason to buy a barrel for one of these pistols, because a threaded Slimline barrel lets you run a compensator or a suppressor.
The holster problem nobody warns you about
The 43X and the 48 share a frame, but the 48's slide is 0.79 in longer (6.85 against 6.06 in), so a closed bottom 43X holster won't take a 48.
Buy a holster listed for your exact variant. Bravo Concealment's Torsion, for one, is listed for the 43, 43X and 43X MOS, says it won't fit a 48 MOS or 48 Rail, and names the red dots it clears.
Then you fit a red dot, a light or a compensator, and the holster no longer works. Streamlight builds the TLR-7 Sub and the newer TLR-7 X Sub in versions for the 43X and 48 Rail and MOS frames. A railless pistol has nothing to clamp either one to.
Buy the holster last, after the pistol is set up the way you intend to carry it. On a Slimline the whole point is a gun that disappears under clothing, and a holster that almost fits defeats it.
Should you carry a Slimline or a Glock 19?
The Slimline exists to be carried. It's thinner than a 19 and conceals better, and it costs you some grip and a little recoil comfort to get there.
If you carry openly or in a bag, or the gun mostly lives in a nightstand, the 19 is a better pistol, and our Glock 19 upgrade guide is the one you want. If the gun has to vanish under a shirt, the Slimline earns its place.
Capacity isn't the trade it used to be. With Glock's 15 round magazine, the 43X and 48 hold what a 19 holds in its standard magazine.
How we pick
We checked every pick against the maker's own page, Glock's spec pages and the live prices at the merchants we track, and prices above are rounded in stock ranges at this update. Where no maker or tester we can link says whether two parts fit, the fit chart says unknown.
Filed underGlock/Magazines/Triggers/Optics/Buyer's Guide
FAQ
Frequently asked questions
Do Glock 19 parts fit a Glock 43X or 48?
- No. The Slimline is a separate parts ecosystem, so magazines, sights, slides and trigger kits from a 19 or 17 won't fit. Makers sell Slimline versions under their own part numbers. The 43X and 48 do share almost everything with each other, differing mainly in slide and barrel length.
What is the best upgrade for a Glock 43X?
- A 15 round magazine. If your pistol came with a 10 rounder, Glock's own 15 round magazine (part number 79269) gets you five more rounds in the same footprint with no catch swap. The Shield Arms S15 with Shield's steel magazine catch is the alternative. Verify your state's magazine capacity limit before ordering.
Do I need to change the magazine catch for 15 round magazines?
- Not for Glock's own 15 round magazine. It's built to run on the factory polymer catch. Yes for the Shield Arms S15, which Shield says needs its steel catch. If you go back from S15s to Glock magazines, refit the polymer catch. Glock built its magazine for that catch. A retailer, Gold Trigger, says it isn't compatible with Shield's steel release, but we haven't found anyone who has tested it.
Does the Glock OEM 15 round magazine fit an older 43X or 48?
- It's built for the same G43X and G48 frame, and Glock says it runs on the standard magazine catch, so owners keep the factory catch. The part number is 79269. Glock announced it on April 17, 2026, due at dealers in May 2026, and said the G43X and G48 will come standard with it, without giving a date.
What red dot fits a Glock 43X or 48 MOS?
- The MOS cut is the Shield RMSc pattern. The Shield RMSc and Vortex Defender CCW mount directly. The Holosun 507K and 407K need a thin plate to clear the slide's rear posts, unless your slide has the newer MOS-K cut (MOSK in the item number), where they mount direct. The Holosun EPS Carry ships with an RMSc plate that clears those posts. The Trijicon RMRcc needs a 43X/48 MOS plate from Trijicon or C&H, and plates from C&H and Forward Controls Design carry RMR, 507C and ACRO sized optics that sit wider than the slide. Glock's full size MOS plates don't fit, and the pistol ships with no plates. Rail and railless slides have no cut and need milling or an aftermarket slide.
Is the Glock 48 better than the 43X?
- They share a frame, magazines and fire control, and differ in slide and barrel length. Glock lists the 48 MOS with a longer barrel, a longer sight radius and about two ounces more weight than the 43X MOS. The 43X's shorter slide is the easier one to conceal.
Should I buy a Slimline or a Glock 19?
- It depends on how you carry. The 48 is the same length and height as a Glock 19 but narrower and lighter, so it conceals better under clothing, and with Glock's 15 round magazine it holds what a 19's standard magazine holds. You give up some grip and recoil comfort. If you carry openly, carry in a bag, or the pistol mostly stays at home, the 19 is the better gun.
Written by
GPP Editorial TeamAR Build Specialists
GunPartPicker guides are powered by data from real builds. What builders actually select tells the story.
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Tools for this guide
- Compatibility toolGlock Size ComparisonPick any two Glocks and see them to scale as real photos sized to Glock's published dimensions, side by side, from behind and as an X-ray, with the difference in length, height, width and weight in one line and the pistols in stock for each.
- Compatibility toolGlock Red Dot Fit CheckerPick how your Glock slide is cut and see which red dots mount directly, which need a plate, and the plates and optics in stock right now.
- Compatibility toolFRT and Binary Trigger PickerChoose your platform and see every forced reset trigger, binary trigger and Super Safety the catalog carries for it, what the host needs to run one, and where each is in stock.