The Glock 21SF delivers high-capacity .45 ACP in a reduced-grip frame, making it a practical choice for duty, home defense, and range applications where terminal performance and shooter control both matter.
Whether you're running the SF as a duty sidearm, bedside defensive pistol, or range workhorse, proper accessories transform this full-size platform from capable to optimized.
This guide covers holsters, weapon lights, optics, magazines, and performance upgrades that maximize the Glock 21SF's potential across defensive and training roles.
Holsters for Glock 21SF
Glock 21SF holsters must accommodate the pistol's full-size dimensions, 13+1 capacity weight, and increasingly common weapon light and optic combinations.
Quality holsters provide secure retention through adjustable tension screws or active retention mechanisms while fully covering the trigger guard and allowing consistent draw strokes.
Modern defensive setups typically incorporate light-bearing holsters that index retention off the light body rather than the frame, requiring holster selection that matches your specific light model.
IWB Holsters
Inside-the-waistband carry suits concealed applications where clothing coverage allows, though the 21SF's size and weight demand robust belt support and proper cant adjustment.
Quality IWB holsters for full-size .45s use reinforced mouths to prevent collapse during one-handed reholstering and provide adjustable retention to maintain security during movement.
OWB Belt Holsters
Outside-the-waistband holsters remain the preferred 21SF carry method for duty, range, and home defense applications, distributing the pistol's substantial weight across a larger belt surface while enabling faster access than IWB. Duty-grade OWB holsters incorporate active retention devices and reinforced construction that maintain security through physical confrontation and vehicle operations.
OWB Paddle Holsters
Paddle holsters eliminate belt threading via wide paddles that slide inside the waistband, making them practical for range sessions or situations requiring frequent removal. The paddle distributes the 21SF's weight across a larger waistband area than standard belt clips, though retention security typically suffers compared to traditional belt holsters during vigorous activity.
Hook & Loop Holsters
Hook-and-loop mounting systems attach to plate carriers, vehicle interiors, or tactical surfaces via industrial-strength hook-and-loop, providing quick positioning for non-traditional mounting locations. These holsters suit vehicle-mounted defensive roles or tactical applications where conventional belt mounting proves impractical.
Drop Leg Holsters
Thigh-mounted drop-leg rigs position the 21SF lower on the body, clearing plate carriers and bulky tactical gear while maintaining accessibility. Adjustable leg straps distribute weight across the thigh rather than the waistline, though proper adjustment remains critical to prevent holster migration during movement.
Chest Holsters
Chest rigs keep the 21SF accessible during ATV riding, hunting, or activities where belt carry interferes with backpack hip belts or seated positions. Quality chest holsters use padded adjustable harness systems to distribute weight across shoulders and prevent bouncing through rough terrain.
Lights for Glock 21SF
The 21SF's integrated rail accepts standard 1913 Picatinny weapon lights, with target identification capability being critical for defensive applications where positive identification prevents tragic mistakes.
Defensive loads demand reliable illumination—500–1000+ lumens proves adequate for most applications, with higher outputs providing additional reach for outdoor or long-distance scenarios.
Popular Weapon Light Options
Streamlight TLR-1 HL and TLR-7A offer proven reliability at 1000 and 500 lumens respectively, providing adequate output for defensive roles with widespread holster compatibility.
SureFire X300 Ultra delivers 1000 lumens with legendary durability suited to duty applications, though at premium cost. Olight PL-Pro Valkyrie provides 1500 lumens at mid-range pricing, though holster availability and long-term reliability reports vary compared to Streamlight and SureFire.
When selecting lights, prioritize models with extensive holster support from major manufacturers to avoid custom holster expenses.
Light-Bearing Holster Requirements
Weapon lights change pistol dimensions, requiring light-specific holsters that accommodate both firearm and illumination device profiles.
Most manufacturers produce 21SF-specific holsters for popular lights—TLR-1, TLR-7, X300U—with retention indexed off the light body and frame.
Universal light-bearing holsters accommodate multiple lights through oversized openings but sacrifice precise retention and may allow unwanted movement. Always verify holster compatibility with your specific gun-and-light combination before purchase.
Activation and Control Methods
Ambidextrous tail switch activation allows support-hand momentary activation during two-handed shooting, while constant-on modes suit scanning operations.
Practice light manipulation during dry fire to develop muscle memory for activation under stress—most defensive shooters use momentary activation for threat identification followed by immediate disengagement to avoid target fixation.
Remote switches suit tactical applications but add complexity and potential failure points for defensive use.
Optics for Glock 21SF
The 21SF predates factory-optics-ready slides, requiring slide milling or dovetail adapter plates for micro red dot installation.
Properly mounted optics improve target acquisition speed and precision, particularly under stress where iron sight alignment suffers.
Competition and defensive shooters increasingly adopt slide-mounted red dots for the acquisition speed advantages they provide across lighting conditions.
Slide Milling Options
Professional slide milling creates precision-cut mounting surfaces directly into the 21SF slide, accommodating Trijicon RMR, Holosun 507C, or similar micro red dots with lower mounting heights than adapter plates.
Quality milling services include backup iron sight retention via suppressor-height front sights, allowing iron use if optics fail. Properly milled slides maintain structural integrity while providing rock-solid mounting platforms that maintain zero through .45 recoil.
Dovetail Mount Plates
Dovetail mounting plates attach through the rear sight cut, offering red dot capability without permanent slide modification.
These plates trade slightly higher sight lines for installation reversibility and lower cost compared to milling. Multiple manufacturers produce Glock-specific dovetail mounts accepting various optic footprints, though users must verify compatibility with the 21SF's specific sight dovetail dimensions.
Red Dot Selection
Holosun 507C offers multiple reticle options, solar backup, and proven durability at mid-range pricing. Trijicon RMR Type 2 provides legendary reliability and clear glass suited to duty applications where failure isn't acceptable.
Shield RMSc and similar compact dots work well on milled slides where minimal profile matters. Battery life, reticle size, and window clarity drive selection alongside mounting compatibility with your chosen installation method.
Backup Iron Sights
Micro dot installations should preserve backup iron sight capability through suppressor-height front sights and appropriate rear sight configurations.
Lower-1/3 cowitness allows dot use while maintaining iron sight visibility in the lower window, whereas absolute cowitness places dot and irons at identical heights. Defensive users prioritize iron sight retention for redundancy, while competition shooters may skip backup irons to maximize sight picture.
Magazines for Glock 21SF
Factory 13-round magazines represent the reliability baseline, with proper magazine selection and maintenance directly affecting defensive reliability.
Most 21SF users maintain multiple factory magazines for defensive use while exploring aftermarket options for training or capacity-restricted jurisdictions.
Factory Glock Magazines
OEM 13-round magazines deliver consistent function across ammunition types with robust steel-lined polymer bodies and properly-tensioned springs.
Factory magazines maintain reliability through thousands of cycles when properly maintained. Some early 21SF runs used magazines with additional front cuts for ambidextrous magazine releases, creating compatibility considerations with standard G21 magazines—most current 21SF pistols accept standard 13-round G21 magazines without issue.
10-Round Magazines
Capacity-restricted jurisdictions require 10-round magazines that maintain similar external dimensions to standard 13-rounders but incorporate internal blocking.
Factory 10-round magazines provide reliable alternatives for compliance requirements, though users should verify local regulations regarding magazine possession and transport.
Magazine Extensions
Competition magazine extensions from aftermarket manufacturers add 2-4 rounds beyond factory capacity while improving reload indexing through enlarged base pads.
These aluminum or polymer extensions attach via modified base pad hardware and may require extended magazine springs for reliable feeding. Extensions primarily suit competition and range use rather than defensive roles where OEM magazines remain preferred.
Magazine Maintenance
.45 ACP's larger case dimensions require clean magazine bodies and properly-tensioned springs for reliable feeding. Inspect magazines regularly for damaged feed lips, worn followers, or weakened springs that cause feeding failures.
Replace magazine springs every 5,000-10,000 rounds or whenever feeding issues develop. Mark magazines individually to track round counts and identify problematic units before they cause defensive failures.
Grips and Grip Enhancements for Glock 21SF
The SF grip already reduces circumference versus standard G21 frames, improving trigger reach for average-sized hands. Additional grip modifications address texture, palm swell, and recoil management for shooters wanting enhanced control during rapid fire.
Grip Tape and Textured Wraps
Skateboard-style grip tape or purpose-designed firearm grip tape provides aggressive texture that maintains purchase through moisture, though installation requires careful application to avoid bubbling or premature wear.
Textured rubber sleeves like Talon Grips offer less aggressive but more comfortable texture suited to extended range sessions or concealed carry where clothing abrasion matters.
Stippling Services
Professional frame stippling creates permanent aggressive texture through controlled melting of the polymer surface.
Quality stippling services like Boresight Solutions or Agency Arms provide consistent texture depth and patterns that improve control without excessive abrasiveness. Stippling permanently modifies the frame, affecting resale value and warranty coverage.
Grip Reductions
Custom grip reductions remove material from the backstrap and sides, further decreasing circumference beyond the SF frame for shooters with smaller hands.
These permanent modifications require professional gunsmithing to maintain structural integrity and proper trigger geometry. Most 21SF users find the factory SF grip adequate without additional reduction.
Triggers for Glock 21SF
The factory trigger connector and spring combination provides 5.5-pound pulls suitable for duty applications, though aftermarket components allow tuning for competition or personal preference.
All trigger modifications must preserve safe drop safety and prevent uncommanded discharges.
Aftermarket Trigger Connectors
Aftermarket connectors from Ghost, Lone Wolf, and similar manufacturers reduce trigger pull weights to 3.5-4.5 pounds through modified geometry.
These connectors maintain factory safety systems while delivering cleaner breaks and reduced take-up. Defensive pistols should maintain 4+ pound pulls to prevent unintentional discharges under stress or during legal scrutiny.
Trigger Spring Combinations
Reduced-power striker springs and trigger springs decrease pull weights but risk light strikes with hard primers if excessively light.
Quality spring combinations from reputable manufacturers balance pull weight reduction against reliable ignition. Always verify reliable ignition with your defensive ammunition after spring changes—light strikes with defensive loads represent unacceptable failures.
Complete Trigger Assemblies
Drop-in trigger assemblies from Apex, Overwatch Precision, and Agency Arms provide comprehensive upgrades including improved trigger shoes, optimized connectors, and tuned spring weights.
These assemblies simplify installation versus piecemeal modifications while delivering consistent performance. Premium assemblies maintain drop safety and include detailed installation instructions.
Sights for Glock 21SF
Factory polymer sights work adequately for general use, but steel night sights or fiber-optic upgrades dramatically improve target acquisition across lighting conditions.
Sight upgrades remain among the most cost-effective performance improvements for defensive pistols.
Night Sights
Tritium night sights from Trijicon, Meprolight, and XS Sights provide self-luminous aiming points in complete darkness, critical for home defense where light switches may not be accessible.
Three-dot systems provide complete sight picture visibility, while two-dot configurations (tritium rear only) reduce rear sight distraction during rapid shooting. Tritium brightness fades over 10-12 years requiring eventual replacement.
Fiber-Optic Sights
Fiber-optic front sights gather ambient light into brilliant aiming points that accelerate acquisition under varied lighting.
Competition shooters pair fiber fronts with plain black rears to create high-contrast sight pictures supporting rapid target transitions. Multiple fiber colors suit different lighting preferences—green typically provides the brightest daylight visibility.
Suppressor-Height Sights
Suppressor-height sights clear common weapon lights and position above slide-mounted red dots for backup iron capability.
These taller sights prove essential for optics-equipped pistols or light-bearing setups where standard sights would be obscured. Quality suppressor-height sets from Ameriglo or Trijicon maintain proper sight radius despite increased height.
Recoil Management Components for Glock 21SF
The 21SF's polymer frame and .45 ACP chambering generate noticeable recoil, though the platform's mass helps manage it compared to lighter alternatives. Aftermarket recoil springs and guide rods provide minimal performance improvements for most shooters.
Guide Rods and Recoil Springs
Stainless steel guide rods replace the factory polymer unit, adding negligible weight while eliminating flex during cycling.
Aftermarket recoil springs in various weights allow tuning for specific ammunition—heavier springs reduce slide velocity with hot loads, while lighter springs improve cycling reliability with target ammunition. Factory springs work reliably for most applications, making aftermarket options primarily relevant for competition or specialized ammunition.
Captured Recoil Systems
One-piece captured recoil assemblies from companies like Lone Wolf simplify field stripping by eliminating loose spring retention.
These assemblies function identically to factory systems but prove slightly easier to manage during cleaning. Most shooters find the factory system adequate, making captured assemblies convenience upgrades rather than performance necessities.
Slide Accessories for Glock 21SF
Slide covers and aesthetic modifications personalize the 21SF while potentially affecting function. Prioritize reliability over appearance for defensive pistols.
Slide Cover Plates
Aftermarket slide covers replace the factory stamped-steel cover with machined aluminum or brass units featuring custom designs or branding. These plates serve purely aesthetic purposes and should maintain proper firing pin channel sealing. Quality plates from reputable manufacturers avoid creating reliability issues.
Grip Plugs
Grip plugs fill the magazine well opening in the frame, preventing debris intrusion and creating a finished appearance.
These plugs serve cosmetic purposes primarily, though some users appreciate keeping pocket lint from entering the frame. Verify grip plugs don't interfere with magazine insertion or removal.
Cleaning and Maintenance Tools for Glock 21SF
.45 ACP generates significant carbon and fouling that accumulates in the barrel, chamber, and feed ramp. Regular cleaning maintains reliability and accuracy through thousands of rounds.
Essential Cleaning Supplies
Quality cleaning kits include bronze or nylon bore brushes sized for .45 ACP, chamber brushes that reach fully into chambers removing stuck cases and carbon rings, and proper-length cleaning rods that won't damage barrel crowns.
The 21SF's chamber requires thorough cleaning, particularly when switching between ammunition types or experiencing extraction issues.
Specialized Glock Tools
Glock-specific tools include front sight tools that remove factory sights without frame damage, sight adjustment tools for windage corrections, and detail brushes accessing the striker channel and extractor area.
Professional armorer's tools simplify maintenance but aren't required for basic cleaning and function verification.
Lubrication Points
Glock reliability demands proper lubrication at slide rails, barrel lugs, and connector interfaces.
Quality gun oils from Break-Free, Slip 2000, or similar manufacturers provide adequate lubrication for general use. Avoid over-lubrication that attracts debris—light oil films on friction surfaces prove adequate for reliable operation.
Conclusion - Best Glock 21SF Accessories
Outfitting your Glock 21SF with appropriate accessories maximizes its potential across duty, home defense, and training applications.
Quality holsters tailored to your carry method and light configuration ensure secure retention and consistent access. Weapon lights provide critical target identification capability for defensive scenarios.
Slide milling or adapter plates enable modern red dot capability that improves accuracy and acquisition speed. Factory or thoroughly-vetted magazines maintain feeding reliability that defensive applications demand. Night sights or fiber-optic upgrades dramatically improve target acquisition across lighting conditions.
Whether you're running the 21SF for duty, bedside defense, or range work, these accessories transform a capable factory pistol into a fully optimized defensive system matched to your specific requirements.