The Glock 21SF is a full-size semi-automatic pistol chambered in .45 ACP. The SF designation refers to the Short Frame grip, which reduces the circumference slightly compared to the standard G21. The 4.61-inch barrel and 13+1 double-stack capacity are carried over from the standard model. Weight is 29.3 oz (1.83 lbs) unloaded. The frame is polymer; the slide is forged steel. 
 

Key Specifications 

• Manufacturer: Glock 
• Model: G21SF 
• Caliber: .45 ACP 
• Barrel Length: 4.61 inches 
• Capacity: 13 rounds (Double Stack Magazine) 
• Weight: 29.3 oz (1.83 lbs) 
• Frame Material: Polymer 
• Slide Material: Forged Steel 
• Trigger Pull Average: 5.5 lbs 
   

Detailed Features 

• Safe Action System: Three passive safeties (trigger, firing pin, and drop), all disengage together when the trigger is pulled and reset when released. No external manual safety. 
• Short Frame grip: The reduced grip circumference is the primary difference from the G21 and addresses the common complaint that the G21 was too large for shooters with smaller hands. 
• Textured polymer grip: The factory texture handles moisture and gloves without modifications. 
• Fixed sights: White dot front, outlined rear. Basic but functional for factory equipment. 
• Rifled carbon steel barrel: 1:15.75 twist rate. 
• Accessory rail: Accepts standard rail-mounted lights and lasers without an adapter. 
   

Usage Scenarios 

 
The G21SF covers the same ground as any full-size .45 ACP pistol: home defense, range use, and duty carry where concealment isn't required. The 13+1 capacity gives it more rounds than most single-stack .45 designs. The SF grip makes it accessible to a wider range of hand sizes without sacrificing capacity.

Discussion on the Glock G21SF in .45 ACP is consistent with what you see across full-size Glock threads, with the SF-specific ergonomics added in.

Reliability and durability: Ownership satisfaction in terms of reliability is high. The G21SF gets the same "just runs" reputation as the broader Glock line, and this shows up consistently in forum discussions and reviews.

Short Frame grip: The SF designation draws positive comments from users who found the standard G21 grip too large. Users with medium hands frequently report the SF fits better without needing aftermarket backstraps. This is the primary reason most buyers choose the SF over the standard G21.

.45 ACP stopping power: The caliber choice comes up often in defensive-use discussions. Users who prioritize large-caliber terminal performance choose it deliberately and are generally satisfied with how the G21SF delivers it.

Accessory rail: The rail gets mentioned positively for light and laser mounting without extra hardware.

Size for concealed carry: The G21SF is a full-size pistol and this limits its carry options. Users who want to carry concealed in most contexts find it challenging. This is the most common criticism across threads, not that the gun performs poorly, but that the dimensions make it impractical for everyday concealed carry compared to compact .45 options.

Safe Action System: The lack of an external manual safety divides opinion in the usual way. Users who prefer a simpler manual of arms appreciate it; those coming from hammer-fired pistols with manual safeties sometimes find the omission uncomfortable until they adjust.