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Red dots for micro-compact pistols

By Andrew Terrebonne. Published October 12, 2026.

Small slides are where the answer to “will it fit” changes most from one model to the next. The slides below, from 8 different mount systems, reach between 2 and 31 of the 77 optics tracked here. Each section says how that slide is cut, how many optics mount with no plate, how many need one, and what the maker says about its screws.

SlideNo plateWith a plateNo route
GLOCK Slimline MOS (43X / 48)
43X MOS, 48 MOS		151646
Springfield Hellcat OSP cut (Micro footprint)
Hellcat OSP, Hellcat Pro, Hellcat Pro Comp OSP		151448
GLOCK Slimline MOS-K
43X / 48 MOS-K		22055
SIG P365 optic cut (RMSc pattern)
P365 Optics Ready, P365X, P365XL, P365-XMACRO / XMACRO Comp, P365 Fuse		22055
RMSc-pattern direct cut
XD-S Mod.2 OSP		22055
S&W M&P Shield Plus optics-ready cut
M&P Shield Plus Optics Ready		15656
S&W M&P Shield M2.0 optics-ready cut
M&P Shield M2.0 Optics Ready		0374
SIG-LOC slide — P365
P365X / P365-XL / P365-AXG Legion (SIG-LOC slide)		2075

Counted with the fit checker’s resolver against all 77 optics, on the first model listed in each row (the others share the cut). “No plate” includes optics that mount to a cross-compatible cut.

GLOCK Slimline MOS (43X / 48)

Milled for the RMSc pattern: four recoil bosses, two at the front of the cut and two at the rear, and M4 screws. GLOCK's own page says the standard cut fits the Shield RMSc footprint, and that no adapter plates come with these pistols. An RMSc-pattern optic bolts straight on. A Holosun K optic does not: its underside is cut for two bosses, so on this four-boss cut it needs a plate. GLOCK's later MOS-K slide takes either a Holosun K or an RMSc-pattern optic with no plate; the item number on the box ends in MOSK rather than MOS.

No plate15
With a plate16
No route46
Optic screw threadM4 × 0.7
ScrewsGLOCK says the standard Slimline MOS cut takes M4 screws; SIG's ROMEOZero-ELITE manual gives them as M4 × 0.7 for the 43X MOS.

Optics that mount with no plate (15):

and 3 more on the 43X MOS page.

Springfield Hellcat OSP cut (Micro footprint)

Milled for what Springfield calls its Micro footprint, the Shield RMSc pattern: an RMSc-pattern optic, Springfield's own Hex Wasp included, bolts straight on. A Holosun K optic takes a plate: C&H says its plate is what lets a 407K or 507K go on without modifying the slide's recoil posts.

No plate15
With a plate14
No route48
Optic screw threadM4 × 0.7
ScrewsSpringfield's Hellcat manual calls for M4 × 0.7 optic screws, and says a screw must not stand more than 2.4 mm (0.095 in) proud of the bottom of the optic.

Optics that mount with no plate (15):

and 3 more on the Hellcat OSP page.

GLOCK Slimline MOS-K

Later slim-slide cut that takes either the Holosun K or the RMSc pattern with no plate. Takes M3 screws, not the M4s of the earlier Slimline MOS.

No plate22
With a plate0
No route55
Optic screw threadM3
ScrewsTapped M3, not the M4 of the earlier Slimline MOS. The two slim GLOCK cuts look alike but take different screws; mixing them up is the most common cross-threading mistake on slim GLOCKs.

Optics that mount with no plate (22):

and 10 more on the 43X / 48 MOS-K page.

SIG P365 optic cut (RMSc pattern)

Milled for the Shield RMSc pattern. No plate is needed. Holosun K optics bolt on directly as well. P365 SIG-LOC slides are a different cut, listed separately.

No plate22
With a plate0
No route55
Optic screw threadM3 × 0.5 or M4 × 0.7, by slide
ScrewsSIG tapped early P365 optic cuts M3 × 0.5 and later ones M4 × 0.7, and sells a screw set for each. The model name doesn't tell you which slide you have; SIG's screw-set page shows both.

Optics that mount with no plate (22):

and 10 more on the P365 Optics Ready page.

RMSc-pattern direct cut

Milled for the Shield RMSc pattern. No plate is needed. Holosun K optics bolt on directly as well.

No plate22
With a plate0
No route55
ScrewsNo screw thread is on file for this slide, and slim cuts from different makers are tapped M3, M4 or #6-32. Start each screw by hand. If it binds, stop and check the pistol's manual or ask the maker.

Optics that mount with no plate (22):

and 10 more on the XD-S Mod.2 OSP page.

S&W M&P Shield Plus optics-ready cut

Milled for the Shield RMSc pattern: S&W's own articles say the optics-ready Shield Plus takes the "Shield RMS optic footprint" and "uses the RMSc footprint", and an RMSc-pattern optic bolts straight on. S&W doesn't say a Holosun K optic does (it does say so for the Shield X and the Carry Comp), and C&H sells plates to put a 407K / 507K or an EPS on this slide, so this site lists those. Nameless Arms, which re-machines these pockets for K optics, says it has measured S&W's pockets sloping 0.5 to 0.75 degrees toward the muzzle, enough that some optics run short of elevation.

No plate15
With a plate6
No route56
Optic screw thread#6-32
ScrewsS&W doesn't publish this thread: its manual says to mount the optic with the screws that came with the optic, tightened carefully, and gives no thread or torque. Shield Sights, whose RMSc optics fit this cut, sells #6-32 screws for the Shield Plus Optics Ready, and C&H's plates for this slide come with 6-32 plate screws.

Optics that mount with no plate (15):

and 3 more on the M&P Shield Plus Optics Ready page.

S&W M&P Shield M2.0 optics-ready cut

S&W's manual says the optic-ready slide cutout takes an optical sight with the dimensions of the Shield Mini Sight or the Crimson Trace CTS 1500, and S&W's product page names no footprint. S&W says nothing about the Shield RMSc pattern for this slide, so no optic is listed as bolting straight on; C&H sells a plate for the Holosun EPS family on the M&P 2.0 Shield. If you have one of these slides, check the cut against your optic's footprint before buying.

No plate0
With a plate3
No route74

SIG-LOC slide — P365

SIG sells SIG-LOC slide assemblies across the P365 line: P365X, P365-XL, the .380 integrated-comp XL and the P365-AXG Legion. SIG lists the ROMEO-X SIG-LOC Compact for these slides only. As on the M17/M18 SIG-LOC slide, top-mount optics fit via removable recoil-lug pins, but SIG doesn't publish which pattern the pins give.

No plate2
With a plate0
No route75
Flagged “verify”Published sources for this cut are thin or disagree, so treat the counts above as provisional and check the maker’s current documents.

Optics that mount with no plate (2):

Why the same optic gets a different answer

A slide is cut for one footprint, and the footprint decides everything after it: Shield RMSc and Holosun K are the two small patterns most of these slides use, and an optic from one family does not always bolt to a slide milled for the other (the RMSc and K guide sorts out which direction works). Which plate, and which screw, is on each pistol’s page; the cuts differ even between slides that look alike, which is why the section for each says what its maker documents.

For your pistol and optic

Pick your micro-compact and an optic for the plate, thread, torque and co-witness verdict on that exact pair.

Something on this page wrong? Tell us what it should be, and include a source: nothing changes without one.