Big Bore Plastic G21 SF Gen 3

Glock 21 SF 45 ACP

This is an improvement on the Model 21, but it is still a big gun with little potential for concealed carry.

g21 sf

As soon as we opened the case, we wondered what was different or special about the G21 SF. The barrel length was the same as the standard G21. So was the height. It had a great rail with no less than four cross hatches. But that’s not unique to the SF either. We called Glock to find out how the two guns differed, and here is what they said.

glock 21sf

The trigger housing was changed and an ambidextrous magazine release was installed. Magazines were held in place by a notch on the front face of the magazine. We could see the steel inner liner of the magazines through the inlet. Original G21 magazines cannot be retrofit to the SF, but SF magazines will fit older Model 21 pistols. Above all, the backstrap was shortened by about 0.10 inch to make it easier for smaller hands to reach the trigger. Sure enough, in our August 2005 issue we measured the trigger span to be 3.0 inches. Our model SF registered a 2.9-inch span, which brought it closer to our other test guns that measured about 2.8 from the bow of the trigger straight back.

glock 21 magazine

The addition of a right-side magazine release required that a groove be cut into the front of the magazine body. Magazines supplied with the Glock 21 SF will fit standard Glock 21 pistols, but the old magazine will not work in the new model.

In the hand the G21 SF still had a flat, boxy feeling across the weak side grip, but the SF was nevertheless more pleasant to handle. In fact, we thought the SF did the best job of handling recoil, especially when firing the 230-grain FMJ rounds that produced the most felt recoil.

Each of our test guns were striker-fired pistols with polymer frames. But here are some of the ways in which the Glock differed. The Glock pistol had a smooth progressive feel. We never got to the point in our press where we felt it was taking too long to break.

The sights consisted of a white outlined notch in the rear unit, which was dovetailed into place. The front sight was pinned into the slide and displayed a large white dot.

In terms of field stripping, the latch was a pull-down design that needed to be gripped from both sides. All of our pistols required that the trigger be pulled at some point during the breakdown procedure, but with the Glock, clearing the weapon was even more critical. We recommend visually checking the chamber at least twice on any semiauto because when a magazine is removed, the top round in the magazine can be dislodged. Seeing a round fall away from the gun can fool you into leaving the chamber loaded.

Once cleared, the slide of the Glock is released into battery position, and the trigger is pressed. The slide is then shifted to the rear just far enough to allow the latch to drop. No more than a tenth of an inch is necessary. The beauty of the Glock design is that no extra parts fall away, and replacing the slide is as simple as reapplying it to the frame.

At the bench we never put the G21 SF down without unloading it first. One of our staffers said they prefer to carry a gun with a safety or, at least a decocker.

Overall average for five shots was about 1.1 inches across. But when firing the Hornady 185-grain JHP rounds, the SF was a close second with all but one group breaking the 1-inch barrier.

In our action test the Glock scored the highest. We put 19/20 hits inside the A-zone, and 7/10 in the smaller B-zone.

gun test glock

Originally Published In July 2007.

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