Skip to content
firearmlab.
Firearm modelsModels
1,027
PartsParts
5,395
FitmentsFits
121,240
Contribute

GLOCK 21 MOS

Explore parts, discover makers and check what fits your model.

67 documented listings87 fit unconfirmedBrowse categories ↓

Only you can see your saved models.

Ask about a part →Showcase your build →

Choose a part to see sources and fitment details.

What the compatibility labels mean
How we knowHow we check compatibility
  • Lab testedFit checked by Firearm Lab for the recorded setup.
  • Documented fitmentSupported by manufacturer, partner, or reviewed community evidence.
  • Interface matchMounting details match, but this exact model and part have not been confirmed to fit together.

Check your exact model and part before ordering. Fitment limits

Model details
Manufacturer
GLOCK
Model & version
Glock 21 · MOS
Mounting details
Glock MOS, Glock Accessory Rail
Compatibility records
154

Lights & rail fitment

Lights & Lasers

57 listed
View all 57 parts

Sights

Sights

46 listed
View all 46 parts

Optics & footprint adapters

Optics

3 listed
View all 3 parts

Optic Plates

40 listed
View all 40 parts

Triggers & internals

Triggers

8 listed
View all 8 parts

Also on this pistol

Holsters

5 makers

Check each manufacturer’s options for your model, light and optic.

Holster makers (5)

Suggest a missing part →

Categories with no listings (12)

About the GLOCK 21 MOS

Manufacturer listing ↗ · Checked 2026-08-02

Type
Pistol
Manufacturer
GLOCK
Model & version
Glock 21 · MOS
Caliber
45 ACP
Mounting details
Glock MOS, Glock Accessory Rail
Width
1.38"
Height
5.51"
Weight
25.93 oz
Slide width
1.12"
Slide length
7.52"
Barrel length
4.61"
Overall length
8.07"

Other versions of the Glock 21

Compare versions and check the details for your exact model.

  • GLOCK 21Adds: Glock rear-sight dovetail (standard and Slimline slides). Lacks: Glock MOS.
  • GLOCK 21 Gen 2Adds: Glock rear-sight dovetail (standard and Slimline slides). Lacks: Glock MOS, Glock Accessory Rail.
  • GLOCK 21 Gen 3Adds: Glock rear-sight dovetail (standard and Slimline slides). Lacks: Glock MOS.
  • GLOCK 21 Gen 4Adds: Glock rear-sight dovetail (standard and Slimline slides). Lacks: Glock MOS.
  • GLOCK 21 Gen 5Adds: Glock rear-sight dovetail (standard and Slimline slides). Lacks: Glock MOS.
  • GLOCK 21 SFAdds: Glock rear-sight dovetail (standard and Slimline slides). Lacks: Glock MOS.
  • GLOCK 21 V MOSSame recorded mounting details. Check each part for additional requirements.