Glock 20 SF 10mm Auto Pistol

By the Guns and Shooting Online Staff

G 20 SF
Illustration courtesy of Glock, Inc.

We thoroughly enjoyed shooting the G20C compensated 10mm pistol we reviewed in 2006 (see the Product Reviews index page), so for 2012 we decided to review the small frame, non-compensated version. Reviewing Glock pistols is somewhat monotonous, in a good way. No special preparation is required. They are easy to operate, accurate, comfortable to shoot, lightweight and totally reliable. There are no surprises and nothing goes wrong. "Glock Perfection" is more than a sales slogan for Glock pistols.

Takedown is simple without any tools and, unlike pistols where you must remove the slide stop or barrel bushing, there are no small parts to lose. When you field strip a Glock for cleaning, it breaks-down into four large parts: the frame assembly, slide assembly, recoil spring assembly and barrel. No internal parts come loose or fall out. Cleaning can be as simple as dropping the four groups into a container of Prolix cleaner/lubricant for a few minutes. Shake and wipe off the excess Prolix when you remove the four groups and slap the pistol back together. This, no fooling, is what many professional police armorers do. No wonder Glock pistols are the choice of 65% of police departments across the U.S.

The history of Glock pistols has been covered in some detail in previous articles, so we will not go into it here. Suffice to say that Gaston Glock started designing the seminal G17 with a blank sheet of paper and his polymer framed wonder pistol has had a greater impact on autoloader design than any gun since John Browning's famous Model 1911. Today, virtually every major pistol manufacturer, except Colt, offers a polymer framed model and several are shameless copies of the Glock design. If being copied is the sincerest form of flattery, the Glock pistol may well be the most "flattered" autoloader in history. All Glock pistols, from the smallest to the largest, are based on the same Glock Safe Action and most internal parts are interchangeable between models.

The G20 is Glock's most powerful pistol and one of the most powerful autoloaders on the market. It is chambered for the potent 10mm Auto cartridge that generally delivers around 529-647 ft. lbs. of muzzle energy with factory loaded ammunition, depending on the specific load chosen. 550 ft. lbs. is about average, which is comparable to the full power .357 Magnum revolver cartridge. The four major U.S. ammunition manufacturers, Remington, Winchester, Federal and Hornady, all offer 10mm Auto factory loads, as do most specialty ammo companies.

To illustrate how much power the G20 packs in its 15 round magazine, let's do an (admittedly unfair) comparison with a typical .45 ACP pistol with an eight round magazine and bullets of similar sectional density. We'll use 550 ft. lbs. as a representative average for full power 10mm ammo with a 180 grain bullet (SD .161) at a MV of 1180 fps and 405 ft. lbs. as a representative average for .45 ACP ammo with a 230 grain bullet (SD .162) at a MV of 890 fps. With the .45 and a full magazine, you hold 3240 ft. lbs. of total energy in your hand (8x405=3240). With the G20 and a full magazine, you hold 8250 ft. lbs. in your hand (15x550=8250). Each 10mm bullet is 36% more powerful than each .45 bullet and the G20's total available energy is over 2-1/2 times that of the .45. In addition, the easy to carry G20 SF weighs 14 ounces less than an eight shot, .45 ACP, 1911 pistol we recently reviewed.

This illustrates why the G20 is the only common autoloading pistol we recommend for protection in the field if large predators are a potential threat. The best 10mm loads for protection in the field probably use 200 grain bullets (SD .179) to maximize penetration. Cor-Bon, for example, offers their 200 grain RN Penetrator bullet in a 10mm Auto factory load at a MV of 1125 fps and ME of 565 ft. lbs. That is load #HT10200PN/20. Incidentally, Glock offers a 6" replacement barrel for G20 owners who wish to hunt with their 10mm pistol.

The midrange trajectory of a 180 grain 10mm bullet (MV 1150 fps) over 100 yards is about 3.5", so a G20 can reasonably be zeroed at 100 yards for hunting without undue concern about shooting over at intermediate distances. We'd recommend limiting shots to about 50 yards on deer size (CXP2) game, due to the limited energy available. We recommend the same range limitation for full power .357 Magnum revolver loads, which deliver a similar amount of energy.

Glocks are certainly among the most complete autoloading pistol packages sold today. Our test G20 SF came in a foam padded, double hinged, double latched, plastic carrying case. Inside, in addition to the pistol itself, were two magazines, a loader, cleaning rod, nylon bore brush, gun lock, two fired cases, owner's manual and the usual paperwork.

The "SF" (small frame) designation on our G20 test gun indicates that it has a reduced circumference receiver in the backstrap area. This makes it fit medium and small hands somewhat better than the standard size (large frame) G20 version. However, it accepts the same double stack 10mm Auto magazines, which hold 15 cartridges, so this SF pistol's grip is still rather large compared to the medium frame (9x19mm, .357 SIG and .40 S&W) Glocks. This is good, as it spreads the recoil of the powerful 10mm Auto cartridge across a larger area of the shooting hand. The lower bore axis of the Glock reduces muzzle rise.

The Glock's polymer frame contributes to recoil reduction. This material contains no fiberglass, is corrosion free, resistant to climatic conditions, color stable, resistant to lubricants (including Prolix), absorbs recoil and requires virtually no maintenance.

After market manufacturers have devised a wide array of accessories to "improve" Glock pistols. Since the basic Glock is arguably the best and most reliable autoloading pistol in the world, very little improvement is necessary or desirable. We would go so far as to council that the only worthwhile after market internal part is a target trigger connector. (Glock supplies this part only in their "Long Slide" target model pistols and refuses to sell it separately.) An after market target connector will probably set you back about $12, which is outrageous for a small piece of stamped metal, but a worthwhile purchase nevertheless.

Glock trigger pulls with the standard connector are supposed to measure about 5.5 pounds. We have consistently found them to run about two pounds heavier and our test pistol was no exception. We installed an after market "target connector," which is supposed to produce a 3.5 pound trigger pull. Also as usual, this actually reduced the trigger pull to about what Glock claims for the stock connector. In the case of our G20 SF, its trigger pull measured 5.75 pounds after the installation of the target connector.

Changing connectors only requires using a punch (or something similar) to remove the two pins in the frame above the trigger. Although a 3/32" punch is the recommended tool for removing the pins, we installed this target connector at the shooting range using the end of a small hex wrench for a punch. Install the smaller diameter top pin first when reassembling the pistol, then the larger diameter lower pin that retains the slide catch.

Check to see if the trigger bar drags on the inside of the frame when the trigger is pulled. If it does, bend the trigger bar slightly away from the frame. While the pistol is apart to install the new connector, it is a good idea to stone (polish) the key engagement surfaces. These include the end of the trigger bar where it bears against the connector and the end of the cruciform sear where it bears against the striker tang. Since we installed our target connector on the fly at the range, we postponed polishing these parts. When we get around to finishing our amateur trigger job, we expect about a five pound trigger pull.

Glock pistols have changed remarkably little since they were introduced in 1982. One minor change is the provision of a Picatinny accessory rail for mounting flashlights, lasers, etc. underneath the forward part of the frame. Otherwise, the square Tenifer finished Glock slide, squared trigger guard with concave front and polymer frame of our G20 SF look like Glocks have always looked. The all matte black finish is businesslike, but could never be called handsome. Removing some metal from the top corners to round the slide, beveling the front of all Glock slides (per the G34) and a normal, rounded trigger guard would be aesthetic improvements that we wish Glock would make on all of their pistols.

One thing that should not be changed is the grip angle. The Glock (also the Luger, Colt Woodsman, Ruger .22 and similar pistols) points more naturally than 1911 based pistols, at least for shooters not raised on 1911 clones. Try this test: point your index finger straight at something at eye level while curling your other fingers around a long pencil. The angle of the pencil to the line of your pointing finger will probably be virtually identical to the grip angle of a Glock pistol and this is the natural grip angle of your hand.

The success of Glock pistols is primarily due to six key factors. These are identified by Glock as simplicity, durability, reliability, accuracy, safety and ease of maintenance.

  • Simplicity: All Glock pistols are made with 34 or 35 parts. And, as already noted, all Glock pistols use the same Safe Action.
  • Durability: Glock pistols have routinely been subjected to torture tests that would disable other pistols. Many Glocks have fired over 100,000 rounds and still operate correctly.
  • Reliability: Glock pistols have been tested and adopted by police and military units all over the world (including NATO countries.) Almost the only way to jam ("stovepipe" in this case) a Glock is to "limp wrist" it--not hold the pistol firmly when it is fired--and this is considered a user malfunction, not a pistol malfunction per se.
  • Accuracy: Glock pistols come with hammer forged barrels using hexagonal rifling that is less likely to collect accuracy degrading lead, copper and powder fouling than barrels with standard lands and grooves. Glock barrels often increase in accuracy after firing thousands of rounds.
  • Safety: Glock pistols incorporate three internal safeties: a trigger block safety, a firing pin safety, and a drop safety. Nothing needs to be remembered or manipulated by hand to render a Glock pistol safe before or after firing. All that is necessary is to follow the basic safety rule of keeping your finger off of the trigger until you intend to shoot the pistol.
  • Ease of maintenance: A Glock can be field stripped for cleaning and normal maintenance without tools, and detail stripped using only a 3/32 punch to remove three pins. (In a pinch, anything that can be used to shove out the pins will do, including a small finishing nail, paperclip, etc.)

Minor benefits of the basic Glock design include an extractor that serves as both a visual and tactile loaded chamber indicator and a striker fired, hammerless design that reduces the gun's propensity to catch on clothing when drawn from a concealed carry position. There are no "enhanced" safety levers, slide stops or magazine releases sticking out from a G20 SF. The ultra-reliable Glock polymer-bodied magazines will drop free from the pistol when the release button, located right behind the trigger guard, is depressed. The Glock Safe Action, of course, means that there is no manual safety to fumble or forget.

Glock pistols come with high visibility, Patridge type, combat sights. The square front sight is marked with a white dot and the rear sight "U" is outlined in white. It is an easily aligned, highly visible sight picture. The dovetail mounted rear sight can be drifted laterally for windage and alternative height front sights are available to change elevation. Glock offers adjustable sights and tritium night sights as extra cost alternatives.


  • Action - Safe Action (constant quasi double action mode)
  • Caliber - 10mm Auto
  • Overall length - 8.07" (slide)
  • Height - 5.47" (including magazine)
  • Width - 1.28"
  • Barrel height - 1.26"
  • Sight radius - 6.77"
  • Barrel length - 4.61"
  • Barrel rifling - Hexagonal profile, 1 in 9.84" right hand twist
  • Magazine capacity - 15 (10 round mags available)
  • Weight - 27.51 ounces (without magazine)
  • Weight - 39.51 ounces (with loaded magazine)
  • Empty magazine - 2.64 ounces
  • Full magazine - ~11.46 ounces
  • Trigger travel - 0.5"
  • 2012 MSRP - $637

Naturally, we were looking forward to taking our G20 SF test pistol to the range for some shooting. For this review, Guns and Shooting Online's Chuck Hawks, Gordon Landers, Rocky Hays, Jim Fleck and David Tong were on hand for the shooting chores. Unlike some semi-autos, we expect Glock pistols to work right out of the box, so that is how we test fired the G20 SF. We didn't attempt to clean or lubricate it in any way before shooting our groups for record.

We did our shooting at the Isaac Walton gun range south of Eugene, Oregon. At this outdoor facility they offer covered bench rests and 25, 50, 100, and 200 yard ranges. For record, we fired 25 yard groups at Hoppe's 25 yard Slow Fire Pistol Targets using a Pistol Perch rest on the shooting bench. Three shot groups, instead of our usual five shot groups, were used to conserve our limited ammo supply. (Actually, three shot groups are probably appropriate for a field pistol, since you would almost certainly not get more than three shots at any animal.) The weather was warm and sunny with a high temperature of about 85-degrees and no wind.

Where we live, only a limited amount of 10mm Auto ammo is available locally and it is expensive to special order, so our ammo selection was limited. For test ammo we had Federal Premium 180 grain Hydra-Shok JHP (MV 1030 fps) and PMC 200 grain FMJ Truncated Cone (MV 1050 fps) factory loads. Our friends at Winchester Ammunition contributed a few boxes of their potent Super-X load using a 175 grain Silvertip hollow point bullet at a catalog MV of 1290 fps, one of the hottest 10mm factory loads on the market. The good people at Remington sent us a single box of their Remington/UMC 180 grain Metal Case factory loads (MV 1150 fps), all they could scrape-up. (Ammo seems to be in short supply everywhere at this time.) Gordon Landers contributed some of his reloads, which use a 180 grain Hornady XTP-HP bullet and AA No.2 powder for a MV of 1024 fps.

Shooting Results

  • Winchester 175 grain STHP - Smallest group 1"; largest group 2-1/8"; average group size 1.7"
  • Federal 180 grain H-S - Smallest group 7/8"; largest group 2-1/4"; average group size 1.8"
  • PMC 200 grain FMJ - Smallest group 1-3/8"; largest group 2-1/2"; average group size 1.8"
  • Remington/UMC 180 grain MC - Smallest group 1-1/4"; largest group 2-5/8"; average group size 1.9"
  • Reload 180 grain XTP - Smallest group 1-1/4"; largest group 3-7/8"; average group size 3.1"


The subjective recoil of all the ammo tested was very controllable in the G20. This includes the potent Winchester 175 grain Silvertip factory load. Actually, we felt that the PMC 200 grain FMJ load kicked harder than the fearsome Silvertip. The subjective recoil of the G20 was well below the level of full power .357 Magnum loads, which are approximately equal in ME.

We were able to chronograph three of the 10mm factory loads with our Chrony placed 10 feet from the muzzle. Here are the chronograph (instrumental velocity) results:

  • Winchester Super-X 175 grain Silvertip - 1408 fps
  • Federal Premium 180 grain Hydra-Shok - 952 fps
  • PMC Bronze 200 grain FMJ - 952 fps

Those numbers are not a misprint; the Federal and PMC factory loads averaged identical size groups and the same instrumental velocity from our G20, per our Chrony. Sometimes, coincidence really does happen. Also quite interesting is the unexpectedly high velocity of the Winchester 175 grain Silvertip factory load (faster than claimed) from our G20. This is one potent deer hunting or self-defense load.

We figure that any hunter with a big game pistol needs to be able to deliver groups no larger than 2" at 25 yards, 4" at 50 yards and 8" at 100 yards. That would be for a maximum practical range of 100 yards. As you can see, the G20 SF exceeded that standard with all three factory loads fired by five different shooters. This time out, Jim shot the smallest group, using the Federal Premium Hydra-Shok Personal Defense load. We have spent more time considering the G20 SF as a field pistol in this article, but clearly it would be an exceptionally effective choice for self-defense against human predators.

We also had a limited quantity of .40 S&W factory loads on hand for a special test, since Gordon and Rocky insisted that a Glock 20 would fire and function with .40 S&W ("small and weak") ammunition. This is conceivable, because the .40 is based on a shortened 10mm Auto case and the .40 and 10mm bullets are the same .400" diameter. However, since both cartridges headspace on the case mouth and a .40 S&W cartridge isn't long enough to reach the front of a 10mm chamber, Chuck, Jim and David were skeptical of this claim.

A couple of successful magazine loads convinced the doubters. The G20 fed the short cartridges from its magazine, fired them and reliably ejected the spent cases. The G20 didn't bobble in any way, even with this short, lower power ammunition. We can only presume that the extractor was able to hold the .40 S&W case against the breech face so that the firing pin could hit the primer. We didn't record the .40 caliber 25 yard groups, but they were entirely acceptable for a service pistol. We did, out of curiosity, chronograph the .40 ammo from the G10 and found no difference in velocity between it and a G22 (.40 S&W) pistol that we had along for comparison.

As expected, the G20 SF was completely reliable with proper 10mm ammunition, including Gordon's medium velocity reloads. There were no malfunctions of any kind with any of the ammunition we tested.

The G20 SF is exceptionally accurate for a service type pistol, 100% reliable, versatile, soft shooting for a handgun of this power and simple to operate and maintain. (Glocks will typically shoot thousands of rounds reliably over a period of years without even being cleaned.) We have long respected the 10mm Auto cartridge, the most powerful of all common auto pistol cartridges. Combine the best cartridge with the best autoloading pistol and the result is the Glock 20 SF.

Note: Complete reviews of several Glock pistols, including the G20C, can be found on the Product Reviews page.

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