GLOCK 20 SF 10mm Bear Blaster – Review

U.S.A.-( When venturing out into the backcountry you need to have some sort of firearm on you. A foot race with a bear is not my idea of enjoying the outdoors, and I prefer a more guaranteed method for survival. Fifteen rounds of 10mm Auto should deter bears and any other threat. For that reason, my firearm of choice for woodsy situations is the Glock 20 SF (Short Frame) pistol.

Glock 20 SF 10mm Auto Pistol

The Glock 20 SF is a full-size semi-automatic pistol, featuring a 15(+1) round capacity, and is chambered in the potent 10mm Auto cartridge. Both the power of the 10mm Auto cartridge and the carrying capacity of the Glock 20 SF make it an obvious choice of sidearm when in the woods. While some may argue the 10mm does not feature the “knockdown power” of a .357 magnum, evidence shows that it is still more than adequate for use against bears.

GLOCK 20 SF 10mm Auto
GLOCK 20 SF 10mm Auto

AmmoLand’s Dean Weingarten has reported eight incidents since 2002 where a 10mm Auto pistol was successfully used in defense against a bear attack. Five of those eight incidents reportedly involved some variation of a 10mm Glock pistol. Comparatively, there were nine reported incidents involving a .357 magnum: eight were successful, one result was not as lucky.

What you get with the Glock 20 SF is a modern handgun with a track record of success against North America’s most deadly predator, from a manufacturer known for the reliability of their firearms.

Due to Glock’s general popularity, the G20 SF also receives all the benefits of a very deep aftermarket for attachments, accessories, parts, and holsters. There are available base pads that can add five rounds to the factory magazines for a total capacity of 20 rounds of 10mm. Alternatively, you could grab yourself a few 30-round ETS magazines if that’s your preference, or go with a KRISS +18 round extension for a full onboard 33 rounds.

One notable mention is the availability of .40S&W caliber conversions which can be done by swapping out the factory 10mm barrel for the aftermarket 40cal barrel. While not much cheaper this does provide you with the flexibility of training with a slightly less expensive cartridge in the same platform.

On my own model, I decided to keep it simple by only adding a set of Trijicon night sights and a Streamlight TLR-1 HL weaponlight. Although the G20 SF is a full-size pistol, it is fairly lightweight even when fully loaded with the factory magazines. As someone who enjoys hiking, saving a few ounces on a polymer semi-auto is preferable to carrying a heavier wheel gun. The size of the pistol also lends it to be comfortable to carry. The majority of the time I’m hiking I carry the G20 SF in a Gunfighters Inc. Kenai chest holster.

Glock 20 SF in a Gunfighters Inc. Kenai chest holster.
Glock 20 SF in a Gunfighters Inc. Kenai chest holster.

If there is one drawback to the G20 SF, it would be the inability to mount an optic out of the box. Seeing that the pistol is an older model it is to be expected. If Glock decides to come out with an updated full-size 10mm (not including the G40 Gen4), I hope to see a MOS optic cut on the slide. The upside of the Glock 20 SF being an older model is that you can find it at very good prices today.

On the Range

During the course of a few range days, I put approximately 300 to 400 rounds of 10mm Auto through my Glock 20 SF. My G20 SF experienced no malfunctions throughout those trips to the range. The gun proved accurate for me out to 50 yards and I have no doubt that distance could be furthered. In my hand, the G20 SF is comfortable but could be more comfortable if it featured the Gen5 grips without finger grooves.

Recoil was never much of a challenge but it obviously has more of a kick than your granny’s 22. Although that recoil is noticeable, it isn’t impossible to control for a relatively fast follow-up shot. There is no insane, face-smashing muzzle flip to worry about so long as you have an appropriate stance, but I wasn’t able to come close to a “double-tap” sort of speed. On the other hand, I was able to achieve an accurate and well-paced cadence of fire on an IPSC steel target at 25 yards.

There were two features on the G20 SF that I noticed to be just a little bit small: the magazine release and the slide stop/lock. The magazine release is really inconsequential to me. However, someone with smaller hands might want to replace it with an aftermarket product to avoid having to twist your hand to reach it. The slide stop is similarly a little bit tough to use when the gun is locked back. Over the course of shooting the gun, I felt this problem presented itself less, and I was able to close the slide using my thumb. Either way, you can always rack the slide normally, so I do not see this as a real negative point either, but still worth a mention.

Reloading is obviously just as easy as all other Glocks; drop the old mag and insert the new. This is probably one of the most alluring arguments for the Glock 20 SF over a revolver. The old Fudd belief that if “you can’t do it with six” has definitely been largely left to the wayside. If there is a massive blood-thirsty beast rushing through the woods, I want all the ammo and opportunities that I can to survive.

GLOCK 20 SF 10mm Auto
GLOCK 20 SF 10mm Auto

In the end, my decision to go with a semi-automatic 10mm over a .44 magnum revolver really boils down to my personal comfort with Glocks specifically. Simply put, I have many more hours and rounds fired through semi-autos and various Glock models than I do with revolvers. From those hours and rounds fired, I have developed a trust in Glock’s reputed reliability, and the G20 SF has proven to live up to that expectation. If you are on your way to the backcountry, the Glock 20 SF is the ideal companion to bring along on the trail.

About Duncan Johnson:

Duncan is a firm believer in the Second Amendment and that “shall not be infringed”, which means exactly that. A life-long firearms enthusiast and a graduate of George Mason University, now competing regularly in 3 gun competitions, Duncan is always looking to improve his shooting skills. Duncan is a regular contributor to AmmoLand and assists in the everyday gun-news publishing as an assistant editor.AmmoLand Editor, Duncan Johnson about to go "full semi-auto" at Independent Studio Services

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in a computer simulation, if there was such a thing, I think the bear would win 40% of the time. I carried my .40 Taurus with 15 165gr fmj in WY while on vacation. I felt it would give me a chance but not invincible


Shot placement and penetration is the key.

The willingness and the capability to use your defensive firearm is far more important then what.


I picked up a Rock Island 1911 – 10 mm and I handload 200 grain Buffalo bore casts for it . I pack a Ruger stainless new model Blackhawk .44 Remington magnum for bear defence here in Montana. Not wanting to experience a fail to feed when a griz is in my face ! I feel a revolver is slightly more dependable for bear defence.


desert eagle 50 , have used it in a firefight in Columbian jungle ten 8 round mags never strayed from group again

Desert Rat

Another option is to convert a 1911 or a Glock 21 to .460 Rowland. Now you are throwing a 230gr 1300-1360fps for even more knockdown power. Lone Wolf makes (or used to) threaded .460 barrels for the Glock 21 and a compensator to reduce recoil. .44Mag power with quick magazine reloads.

Charlie Foxtrot

I wouldn’t use the term “knockdown power”, especially with handguns.

A hot 10mm 220 gr hardcast will be 1,200 fps. Will a larger caliber 230 gr .460 Rowland with 1360fps be that much different? As Paul Harrell says: “You will be the judge!”

Now, a .460 Rowland conversion requires a compensator.


I chose a pawnshop G21 with a Storm Lake 10mm conversion barrel and Wolff 21# recoil spring, for its better case support.

Your ammo choice should consider projectile design along with mass and muzzle velocity. The JHP you carry in the city for squishy bipedal assailants, isn’t much use in the mountains against furry fangy unfriendly armored quadrupeds. You need mass retention for bone penetration, not soft tissue expansion. That’s why Buffalo Bore and Underwood and others offer “hard cast” or “monometal” bullets over full-house powder loads.

Henry Bowman

The 10MM is roughly equivalent to the .41 magnum. Although Glock is a decent frame, there’s other brands that offer 10MM. One in particular has gone through a 20k round torture test with literally ZERO malfunctions. It also has a captured spring that mitigates the majority of felt recoil, too. I won’t mention the brand I have in mind because that would trigger (pun intended) all of the Glock fanboys. But I fully intend to get one in the next few months, and till then I’ll be taking my .40S&W with Underwood Extreme Penetrator ammo.

Charlie Foxtrot

Feel free to mention the brand!

By the way, Gen 4 Glocks do have captured recoil springs. Having said that, most people do not know that you need to replace the recoil spring every 5,000 rounds, or so.

Henry Bowman

First off, I see that the resident troll(s) are at it again with the downvotes on me. I guess I’m over the target LOL And for the other, I’ll go ahead & say it; Springfield Armory. Hopefullu I won’t catch hate for this. I like the better versions of the XD series: XDM and XDM Elite. They’re just as good and MAYBE possibly better. SA has been like a magician making their products durable and higher capacity. Before I met my fianceé, she bought a Hellcat for EDC, too (our taste in guns is serendipitous). My first SA was their… Read more »

Springfield Armory XDM 40.png
Last edited 11 days ago by Henry Bowman
Charlie Foxtrot

I am not sure why you are making your post so much about Glock fanboys. Anyway, I think the three main complaints about Springfield are (1) they bought an American armory name to sell foreign-made guns, (2) their guns repeatedly fail in high round count classes and (3) the company supported a certain gun control legislation a few years ago. I personally do not trust “torture test” videos from any company. If you talk to firearms trainers in the US, they will tell you which guns they see fail in classes and why. I gather you do not actually own… Read more »

Henry Bowman

Well, see you’re doing the very thing that pisses me off. 1 When SA got started they DID make USA-made 1911’s and the M1A semiauto copy of the M14. These work fine and do NOT jam up or anything!! Just because they’ve partnered with a European company does not matter; other companies are 100% European and sell through a domestic distributor (thanks to GHW Bush infringing against foreign manufacturers). 2 There is nothing wrong with Euroguns, so don’t knock Springfield for partnering with HS Produkt. Glock, Euro. Sig, Euro. FN, Euro. Beretta, Euro. Tell me again how your eurogun is… Read more »

Last edited 11 days ago by Henry Bowman
Charlie Foxtrot

Seems to me you have a Springfield fanboy problem and can’t be objective. Your problem, not mine.

Use experience reports, not media stunts to make purchase decisions on guns.

Henry Bowman

No, I like many brands, and you’re being a troll, so how about you P!$$ 0FF

Uncle Sam Finger.png
Charlie Foxtrot

I am not the one who doesn’t have a 10mm pistol and just came here to instigate some sort of manufacturer “discussion”.

We get it, you like Springfield Armory. Do you have anything else to contribute?

Henry Bowman

Yes, please feel free to go fornicate yourself, troll. Having a nice conversation with the likes of you is impossible, especially when you’re using sockpuppets to pump yourself up and DV me just as many times. Russ was right about you.

Announce Cat Take Your FAIL and GTFO.png
Charlie Foxtrot

The only one using foul language here is you. I didn’t know that you consider that “having a nice conversation”. Duly noted!

I was having a conversation with you, until you disagreed with me, and just lost it.

I am nut sure who you think I am with your “sockpuppets” accusation. I have no idea what you are talking about in your reference to “Russ”.

Henry Bowman

All I can hear is bzzzzz, bzz bzzz….

Charlie Foxtrot

I thought so. Thank you for confirming.

Henry Bowman

Shut up, troll. It’s bedtime; have a cookie and go to bed!


why not a 44 magnum or 454 for bears

Henry Bowman

Because 10MM is for semiauto, and has the advantage of pistol capacity. It’s a proven fact that multiple well-placed shots always gets the job done. I’d not stop shooting till the beast is immobile.
That being said, I’d be curious to try 454 and see how that shoots!
Works wonders on two-legged predators too. If these predators have kevlar hides, then I’d transition to my AR.

10MM The One Caliber.png

desert eagle in 50 ae with underwood +p+penetrators

Monkey Mouse

I just picked one up earlier this week – can’t wait to hit the range. 10mm ammo is harder to get than 9mm or 40, but about as hard as 357 these days.

Charlie Foxtrot

Make sure you get actual 10mm ammo that is loaded to full power 10mm spec. There is a lot of 10mm ammo out there that is loaded to warm .40 spec. A 180 grain round should have 1,250-1,300 fps.


Charlie I would agree.

Modifying a Glock as you said is unnecessary. Training and practice solves both.

Having shot 1911’s for over 5 decades and Glocks for only around 3 old habits are hard to over come.

That is why ones first training is so important. Just as it hard to over come bad habits. It is just as hard to forget good ones.

Train right the first time.

Charlie Foxtrot

“The magazine release is really inconsequential to me. However, someone with smaller hands might want to replace it with an aftermarket product to avoid having to twist your hand to reach it.” The whole purpose of needing to twist your hand to actuate the magazine release is so that you do not accidentally do it while shooting. An enlarged magazine release will just make that happen for you and you will see magazines flying out of the gun while shooting. “The slide stop is similarly a little bit tough to use when the gun is locked back.” Well, it is… Read more »

Last edited 14 days ago by Charlie Foxtrot

Having shot bears with handguns. I am impressed with what a 315gr hard cast WFN 44 at about 1300fps bullet does to them.

The 10mm has proven to work along with others.

When it comes to handgun calibers used far more bears have been shot with the 44mag.

If you have read Deans stuff even mentioning the “357 failure” you would realize it was operator error not caliber.

Same with the other two “failures”.

The 10mm is what it is better or worse not really it is what it is.


Operator error may depend at least partly on platform used. DA revolver typically is going to have a longer and heavier trigger pull than any glock, making semiauto possibly more forgiving of undertrained user. Ditto on 6 rounds vs 15 (plus reloads) – semi allows pretty rapid fire, together with higher capacity may allow better chance to follow up misses with some hits.

Boils down to user competence, and some luck. Stack the odds by being familiar with whatever you choose to carry and practice until you cannot do it wrong.


AS ALWAYS, it is important to have a lot of practice and dry firing experience to make your sidearm like an extension of your hand. Muscle memory is the luck that might save you when you have an adrenaline dump. For those of you who have never had one, you will have no idea of what I am talking about. For those of you that have had one, YOU know what I mean.


Co for 23 years, 15 with a Model 15, then a Smith 5904. I ever developed the speed, accuracy and fluidity of motion with the auto. Long retired, I carry a Model 19, 4 inch when in the local woods. Fits my hand and hits what I aim at. No auto will do that for me.


funny I feal more solid with 1911 or in the woods desert eagle in 440 or 50ae


ammo choice is a big deal loads that are perfect for urban self defense are not so good with big game


sometimes it is ammo choice hollow points are a nono on large game