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Glock 40 MOS: 10mm Ammo Review

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The Glock 40 MOS has proven itself a top option in 10mm. But when it comes to feeding it, what is the top ammo choice?

What are specs for the Glock 40 MOS:

The resurgence of interest in the 10mm Auto cartridge is attended by a fanciful and ever-growing myth of legendary stopping power. Along with these fantasies flows a mountain of steamy bunk, served like dung on shiny china.

Recoil from the Glock 40 MOS is no walk in the park but is easily controllable thanks to the ergonomics of the Gen 4 Glock’s slimmer pistol grip and long, 6-inch slide.

Regardless of what the bespectacled gun counter guy may claim, the 10mm Auto is not “the .44 Magnum of semi-autos.” Not even close. Nor is it the .41 Magnum of semi-autos. The way many people talk about the 10mm Auto cartridge, you’d think they’re describing the lesser-known but related 10mm Magnum, which was first chambered by Harry Sanders in some of his early Automag pistols and later by Smith & Wesson in the Model 610. That load is a hammer that is not produced commercially today. The 10mm Magnum, of course, bested the standard 10mm Automatic by at least 300 fps and did indeed make .41 Magnum territory.

However, as we discovered in this ammo test, the standard 10mm Automatic, the .40-caliber brainchild of the late Col. Jeff Cooper, is no pussycat. And true to its reputation, it hits like a Mike Tyson uppercut. Testing a Glock 40 MOS (Modular Optics System) — a 6-inch long-slide 10mm and reigning king of hand cannons in the company’s lineup — with a Burris FastFire 3 reflex-style sight, I lit off a bunch of the best 10mm ammunition made today to see what takes the cake for range practice, hunting and personal protection loads. Here are the results.

Trigger Notes

Glock’s striker-fired mechanism feels like a rough double-action trigger, but you must keep the pistol design in context. Glocks are typically used for everyday carry and personal defense, so I can understand a tough trigger. After all, when it comes to self-defense, it makes sense to have a heavy trigger that only trips when it’s intended to be pulled.

The overall winner of our 10mm Auto ammo test was the Underwood 150-grain Xtreme Hunter load. It yielded 1.24-inch average and .53-inch best groups at 25 yards. Best of all, it’s doing 1,415 fps for 667 ft-lbs of muzzle energy. That level of accuracy and horsepower can dominate for hunting, survival, home defense and everyday carry.

But since I wanted a handgun that could also be used for a wider range of tactical and survival scenarios, a lighter, smoother trigger pull to facilitate long-range accuracy was desired. On a hunting handgun, the trigger can’t hinder accuracy on shots that could range from 25 to 50, or even 100 yards. There’s a case to be made for long-range handgun accuracy in a tactical handgun. You never know what you might encounter.

More Information On Glock:

Thankfully, I was able to improve the trigger dramatically by installing a 3.5-lb. connector and spring kit, doing some judicious hand polishing of key mating parts and finishing up with a deburring job that would have made the old machine shop teachers proud. A little elbow grease transformed the Glock trigger into a 3.4-lb. beauty. Considering the Glock’s stellar out-of-the-box accuracy and reliability, it is now fully capable of unleashing hellfire on targets from point blank to 50 yards with alarming precision.

Burris FastFire 3

The little Burris Fastfire 3 reflex-style red-dot sight looks tiny sitting on top of the G40's massive slide, but don't judge a book by its cover. How Burris engineered it to not only keep from flying into the wild blue yonder under the heavy recoil of powerful 10mm loads is beyond me, but what really impresses is how well it holds zero shot after shot after shot. I tried to break it by shooting hundreds of rounds of the hottest loads I could get my hands on. It kept working, didn’t budge. That inspired confidence.

Underwood’s 140-grain Xtreme Penetrator load ranked very high as tested in the Glock 40 MOS. The load uses the Lehigh Defense bullet and penetrates like an anti-aircraft shell. It’s carried by many Alaskans for bear encounters.

The optic uses a 3 MOA red-dot, which has three manual brightness settings and one automatic brightness sensor, which is what I used. Elevation and windage adjustments are accomplished using a small, standard screwdriver in the slots on the top and back. Adjustments are responsive and precise. The FastFire 3 is a simple 1x magnification and was completely parallax free.

The sight was left in the off position while carried, and I practiced activating the left-side On button with my left-hand thumb during the draw cycle. There were no hiccups using this technique, but still uncertainty exists among some shooters. So they install tall suppressor sights on reflex-equipped handguns. The idea is to provide a “co-witness” through the red-dot’s screen and serve as a backup in case of optics failure. I chose not to do that. Instead, I found that for shots at normal defensive ranges of 7 yards and under, you can simply use the screen itself with the optic turned off to bracket an IDPA target. The result is an ultra-fast sight picture — even quicker than obtaining the red-dot — and remarkably accurate. It seems to act as a sort of extra-large rear peep sight. For longer shots, Burris has provided a vertical white line on the back edge of the FastFire 3, which functions as a makeshift rear sight should a backup be needed.

The real surprise in the test was the performance of the 180-grain Trophy Bonded JSP load from Federal. This load scoots a flat-meplat bullet along at 1,355 fps, putting 734 ft-lbs. on target. On top of that, its accuracy was second best of all lots tested — 1.50-in. average and .44-inch best groups at 25 yards.

With all these features, such a rig places a tremendous amount of firepower in your hands. You can dump 15 rounds of heavy 10mm, jack a reload home, unleash another volley and whistle Dixie … all without skipping a beat. That might be a bit overkill on whitetails, but two-legged attackers deserve every bit of it. In case you’re wondering, the era of reflex sights on handguns is here to stay. The technology is ready for prime time. However, when carried all day under a shirt concealed, the little screen on the reflex sight attracts dust like Yogi Bear to a pic-a-nic basket. It's not worth crying about, though — simply blast it clear every few days with a can of compressed air and use the fleece scratch-free cloth provided by Burris to safely wipe the screen clean.

10mm Range Review

For the range test, I shot a selection of 10mm ammo through the Glock 40 MOS. That included practice, personal protection and hunting loads. Representing the range/target loads were Federal 180-grain American Eagle FMJ, Blaser 200-grain FMJ and DoubleTap Colt National Match 180-grain FMJ. Among this group, DoubleTap’s Colt NM loading produced the most consistent accuracy from the Glock 40, with a 1.32-inch average, and a .60-inch best group at 25 yards from a rest. Personal defense choices tested included Hornady’s 180- and 155-grain XTP, and Hornady Critical Duty with a 175-grain FlexLock bullet. Federal’s 180-grain Hydra-Shok, DoubleTap’s 135-grain Controlled Expansion JHP and the Underwood 115-grain Xtreme Defender rounded out the best choices for concealed carry. When it comes to EDC — considering accuracy and sheer foot pounds of energy — it was a dead heat between DoubleTap’s 135-grain JHP and Underwood’s 115-grain Extreme Defender, both of which kept average groups just over an inch at 25 yards and crushed the 700 fps barrier (725 fps and 788 fps, respectively).

DoubleTap’s Colt National Match 180-grain FMJ load proved exceptionally accurate, printing an average 1.32-inch group, and a best .60-inch group at 25 yards from a solid rest.

For the hunting/survival category, there was naturally some overlap with some of the personal defense loads already mentioned, especially the DoubleTap 135-grain JHP load. Federal’s 180-grain Trophy Bonded JSP was a real humdinger. It proved accurate and hard-hitting, with a best 25-yard group of .44 inch and 734 ft-lbs, making it a must-try for whitetails and everyday carry. Underwood’s two screamers — a 140-grain Xtreme Penetrator (a favorite for grizzly bear protection) and 150-grain Xtreme Hunter — were the cat’s meow. The 140-grain load printed very consistent groups that averaged 1.34 inches at 25 yards, with 738 ft-lbs of energy. Even more impressive was Underwood’s 150-grain Xtreme Hunter, the second-most accurate ammunition of the entire test (1.24 average, .53-inch best groups at 25 yards) and still hitting with 667 ft-lbs of muzzle energy. Note that the Underwood loads use the CNC-machined all-copper Lehigh Defense Xtreme Defense bullet, which employs radial flutes that force hydraulic energy outward to build pressure and carve a nasty wound channel without sacrificing penetration.

Federal American Eagle 180-gr. FMJ 1,011 484 4.93 .66
Blaser 200-gr. FMJ 1,023 465 1.72 .49
DoubleTap Colt National Match 180-gr. FMJ 1,179 556 1.32 .60
Hornady Custom 180-gr. XTP 1,210 585 2.12 1.84
Hornady 155-gr. XTP Custom 1,321 601 2.20 1.79
Hornady Critical Duty 175-gr. FlexLock 1,137 502 3.86 1.15
Federal 180-gr. Hydra-Shok JHP 1,071 459 2.22 1.525
DoubleTap 135-gr. Controlled Expansion JHP 1,555 725 1.82 1.16
Federal 180-gr. Trophy Bonded JSP 1,355 734 1.50 .44
Underwood 115-gr. Xtreme Defender 1,757 788 1.41 1.25
Underwood 140-gr. Xtreme Penetrator 1,541 738 1.80 1.34 4.73
Underwood 150-gr. Xtreme Hunter 1,415 667 1.24 .53 3.95


Between today’s hot, full-power 10mm Auto factory loads, and easy-shooting platforms such as the Glock 40 MOS, the effectiveness of truly powerful, high-pressure cartridges can fully be harnessed. For survival against man or beast, hand cannons like these should have a prominent place in your tactical handgun toolbox.

Editor's Note: This article is an excerpt from the Tactical Gun Digest book, available at

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