10-8 Performance
GLOCK 21 Gen 4
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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 · Gen 4
Mounting details
Glock Accessory Rail, Glock rear-sight dovetail (standard and Slimline slides)
Compatibility records
194
Sights
Lights & rail fitment
Triggers & internals
Triggers
28 listed- Agency Arms
Glock DROP-IN TRIGGERS
Manufacturer documented - CMC Triggers
CMC Drop-In Trigger for Glock Gen4 .45
Manufacturer documented - Glockmeister
Trigger Black Shoe Black Safety Gen1 - 4
Manufacturer documented - Johnny Glocks
Factory OEM trigger shoe Upgrade (modified & enhanced)
Manufacturer documented
Recoil Springs
6 listed- DPM Systems
DPM "ADJUSTABLE" System for Gen 4 Glock models: 20-21-41SF
Manufacturer documented - Sprinco
Glock 20/21 Chrome Silicon Moly Plated Cryogenic Processed Recoil Spring - 17# (For use with Sprinco guide rods)
Manufacturer documented - DPM Systems
DPM "CAPTURED" RECOIL SYSTEM for Gen 4 Glock Models: 20-21-41-41SF
Manufacturer documented - Sprinco
Glock 21 Gen 4 COR-BON Recoil Management System
Manufacturer documented
Also on this pistol
Holsters
9 makers- Alien Gear Holsterschecked 2026-11-01
- Blackhawkchecked 2026-11-01
- Concealment Expresschecked 2026-11-01
- DeSantis Gunhidechecked 2026-11-01
- Galcochecked 2026-11-01
- PHLsterchecked 2026-11-01
- Safarilandchecked 2026-11-01
- Vedder Holsterschecked 2026-11-01
- We The People Holsterschecked 2026-11-01
Check each manufacturer’s options for your model, light and optic.
Optics & footprint adapters
Optic Plates
7 listed- Aimpoint
ACRO Rear Sight Adapter Plate for GLOCK
Interface match - C&H Precision
Fits GLOCK Rear Dovetail Adapter Holosun 407K / 507K / C&H EDC / EDC Enclosed / Olight Osight S STEEL
Interface match - Outerimpact
Red Dot Mount – MRA for Glock
Interface match - Shield Sights
Low Profile Slide Mount for GLOCK 21
Manufacturer documented
Barrels & comps
Barrels
3 listed- KKM Precision
21 Match 45ACP 4.6"OAL (Fits Glock G21 Gen 1-4)
Manufacturer documented - KKM Precision
21 Match 45ACP 6"OAL (Fits Glock G21 Gen 1-4)
Manufacturer documented - KKM Precision
21 Match 45ACP with .578×28 Suppressor Threads 5.2" OAL (Fits Glock G21 Gen 1-4)
Manufacturer documented
Compensators
1 listedSlides
Grip & magwells
Magazines
1 listedCategories with no listings (8)
About the GLOCK 21 Gen 4
Manufacturer listing ↗ · Checked 2026-08-02
- Type
- Pistol
- Manufacturer
- GLOCK
- Model & version
- Glock 21 · Gen 4
- Caliber
- 45 ACP
- Mounting details
- Glock Accessory Rail, Glock rear-sight dovetail (standard and Slimline slides)
- Width
- 1.34"
- Height
- 5.51"
- Weight
- 26.28 oz
- Slide width
- 1.12"
- Slide length
- 7.6"
- 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 21Same recorded mounting details. Check each part for additional requirements.
- GLOCK 21 Gen 2Lacks: Glock Accessory Rail.
- GLOCK 21 Gen 3Same recorded mounting details. Check each part for additional requirements.
- GLOCK 21 Gen 5Same recorded mounting details. Check each part for additional requirements.
- GLOCK 21 MOSAdds: Glock MOS. Lacks: Glock rear-sight dovetail (standard and Slimline slides).
- GLOCK 21 SFSame recorded mounting details. Check each part for additional requirements.
- GLOCK 21 V MOSAdds: Glock MOS. Lacks: Glock rear-sight dovetail (standard and Slimline slides).