Should You Upgrade Your Stock Glock Barrel?

Glock has been, and I sure will continue to be, a perennial favorite handgun to run and customize for competitions. The Glock format has also become a favorite for customization with no other tool than a punch. One of the most popular upgrades is to switch barrels to increase accuracy and add the ability to shoot non-jacketed bullets for practice.

There is a huge variety of aftermarket barrels available for the Glock formats including Wilson, Lone Wolf, KKM, and ZEV, notable with KKM and ZEV being the most revered replacement barrels within the 3Gun crowd.

The first thing to get out of the way in this review is that swapping barrels on a Glock is something your average Glock owner could do in a pitch black room. Disassemble the Glock as you would for cleaning, by clearing the gun, dry firing, pull down on the slide releases, remove the slide, pull out the spring and the barrel drops out. Drop in the new upgraded KKM barrel and reassemble – Done!

While working on a comprehensive Glock parts upgrade article for Grandview media, I ended up with a pretty tricked out Glock 19 that I have beat on enough to carry as my daily CCW pistol. The gun features a Deus Ex Machina trigger, PWS billet slide, Trijicon sights, KKM barrel, and Vickers slide & mag release all riding on a limited edition tan frame. After 1000s of rounds the upgraded G19 has proven to be just as reliable as a factory G19, but with some improved features and accuracy. Notably the KKM barrel, PWS slide and DEM trigger really have improved accuracy…with the right premium ammo. This brings me to the point on whether you should upgrade your factory Glock barrel.
Upgraded Glock 19


Aftermarket “Match grade” barrels such as ZEV and KKM have a tighter dimensional fit than the Glock barrels which in turn delivers a tighter lockup than the stock barrel. The chamber itself is also a little tighter and is button rifled vs. Glock’s normal hex rifling. The latter two features deliver improved accuracy with the right ammo (is there an echo in here), however there is a trade off.

From a dependability level, the KKM barrels are still very reliable and function perfectly within factory spec rounds, however I noted with the 9mm barrel used in this build that the KKM barrel would not feed some of my 9mm “turds’ (sloppy reloads) where the stock barrel chews through them just fine.

The button rifling also delivers a trade off. The primary reason Hex rifling was developed was to deliver consistent performance and reliability across a huge variety of ammo, however that all around rifling flexibility does not produce the best accuracy with tight tolerance ammo.

The higher precision button rifling allows shooters to practice with inexpensive cast bullets, where the stock Hex rifling begins to clog/lead up and is therefore not recommended by Glock. Personally I have never seen great groups from cast bullet with my KKM or ZEV barrels. These match grade barrels like premium jacketed bullets made or reloaded to a high level of craftsmanship. Generally I have found that the not-especially-cheap premium 147gr XTP bullets are what my ZEV and KKM barrels really like and perform best with. With those premium rounds the button rifling deliver the improved accuracy you were hoping for.

Another reason for the performance difference with different ammo is that the Glock Factory barrel uses roughly a 1:10 twist rate compared to a very slow 1:16 and 1:20 twist rates of aftermarket barrels. KKMs twist rate is a very slow 1:20 which means that light and very cheap non-concentric rounds are likely to shoot very badly with the KKM barrels.

Cast and inexpensive low tolerance jacketed bullets actually delivered worse groups for me than the stock barrel, but you can at least practice with them. On the other hand, high quality jacketed 147gr bullets, such as those from Hornady and Sierra delivered the best groups I have ever seen out of any Glock. Think of the KKM barrel as a high end sports car. Sure you can go fast running E85, but the engine is designed for premium fuel and delivers big rewards when fed high test fuel. Feed the KKM barrel with great ammo and you get outstanding groups.

Feed these top and barrels low grade ammo and they will likely deliver accuracy which is far worse than you stock Glock barrel. So, with the right ammo the KKM and ZEV barrels can do their job, with cheap ammo and reloads you will be disappointed.
Upgraded Glock Barrel


At a recent range session I was working through some precision slow firing drills and was appalled at the groups I was seeing even at the 7-yard range with my KKM barrel and very inexpensive steel cased MaxxTech 9mm ammo (hey don’t judge, it was really cheap). It appeared that the ammo may have actually been keyholing. Super crappy ammo indeed – I will never buy this stuff again.

Generally with my stock barrel can deliver a single ragged hole from a full magazine of any ammo regardless of quality, but my KKM barrel was printing a 3″+ group. Pushing out to the 25-yard range with cheap MaxxTech ammo and the KKM barrel I would easily fail a standard police qualification test. I slipped in a magazine full of Hornady 147gr XTP rounds and I was rewarded with a index finger sized 7-yard ragged hole and an unsupported 4″ A-Zone 25-yard group – there is the accuracy I was looking for.

I reached into my range pack and pulled out my stock Glock 19 barrel, did the barrel swap, and feed it the same diet of cheap MaxxTech ammo for the first magazine and XTP rounds on the second magazine. The results were stunning. The factory barrel shot a good 1″ ragged hole with the junk ammo and a marginally smaller hole with the premium ammo—that is the magic of the faster twist hex rifling of the factory Glock barrel leveling out everything. The Match Grade Glock barrels are definitely pickier and demand high quality match grade ammo even for practice if you expect to get any advantage out of them. This is just one example and experiment—I have proven this fact over and over to myself that the factory Glock hex rifled barrel is actually pretty freaking awesome with all types of ammo.


The KKM barrel is designed to offer the shooter running premium ammo or premium reloads, the best accuracy one can hope for in a Glock format. Yes, with the right ammo (there it is again), your Glock can consistently deliver 1″-ish 25-yard groups off a rest with a KKM or ZEV barrel. I freaking love my KKM and ZEV barrels and highly recommend them, but don’t feed then cheap ammo.

Would I run a KKM barrel in a defensive pistol? Long ago I said no, but that has changed assuming financially you commit to actually practicing with your CCW carry rounds. So there you have it, if you can swing shooting top of the line ammo all the time or suffer through poor groups with cheap ammo to occasionally reward yourself with tiny little groups the KKM and ZEV barrels are for you. If you plan on shooting whatever is the least expensive, don’t bother with the upgrade; you would be kidding yourself that the upgrade with deliver better accuracy.


KKM Precision
All KKM barrels are made using certified 416R gun-barrel quality stainless steel bar stock. Barrels are heat treated and vacuum tempered to 42 RC. All KKM barrels are CNC machined to obtain superior dimensional tolerances over stock. The advanced proprietary button rifling process allows KKM barrels to offer greater accuracy over stock barrels. KKM’s Glock barrels come with fully supported SAAMI spec match chambers for shooting factory or reloaded ammunition as well as lead or jacketed bullets. Unless noted all barrels are drop-in fit.
Available in Matte Silver or Black Nitride.
Glock Barrels starting at $165.

ZEV Technologies
Zev Technologies Match Grade drop-in Glock replacement barrels feature extremely tight tolerances and are manufactured with pre-hardened chromium stainless steel (416R) that was originally designed for use in Match Grade rifle barrels. This material provides high tensile strength and toughness to withstand typical chamber pressures while still being highly corrosion resistant. ZEV Match Grade barrel bores are some of the most precise in the industry. Every barrel is double honed (rough and finish) until a minimum surface finish of 16 RA is reached. During this process the barrels are held to a final dimension of +/- 0.003″ for consistency and accuracy. The barrels are cut rifled and 100% inspected for groove dimensions and broach finish.
Available in Raw Stainless Steel, Burnt Bronze, and Black DLC (Diamond-Like Carbon).
Glock Barrels a $285 and below.

Have you upgraded your Glock Barrel? Think you might after reading this article? Lets us know by leaving a comment!

15 Comments On This Article

  1. If you reload you might try the 125 grain bullets designed for the 357 Sig. I use the one Montana Gold makes and if is amazingly accurate in all my 9mm guns. (Sig MPX SBR, Sig 239, S&W 952). All of them function flawlessly. I think the reason they are so accurate is the ogive is so short giving the bullet a lot of bearing surface on the rifling. They look like a wadcutter with a really short ogive.

  2. No it’s a waste of money. I did up grade the trigger on all of my glocks. Shorter reset breaks cleaner. Zev complete trigger set up. Huge difference over stock. The Glock barrel allows a use of a wide range of ammo. Except all lead which I do not use.

  3. No, I haven’t purchased any aftermarket Glock barrels, and probably never will. I get <=1.5" groups with practice reloads in 9mm and <=2.5" in .380 (Berry's RNP 115 grain 9mm for my 19 & 43, Rainier RNP 100 grain for my wife's 42). All 3 pistols shoot a bit better with Hornady Critical Defense.

    But I only shoot informal practical defense practice on steel and (with my G19) bowling pins & infrequent IDPA, so I don't compete in anything where group size really matters to me beyond keeping them where I'm looking. Some of my friends, however, shoot IPSC/USPSA and other matches where 1/10" can mean money or not. For their sake, I'm very glad there are tighter tolerance barrels available, as well as all the other custom & mass-produced aftermarket internals & slides & so on.

    The guys I know who really focus on sports where group sizes are key use platforms other than Glock – Bullseye, for example.

    I personally keep my CCW pistols unaltered inside: I had my G19 grip frame reshaped because my short fat fingers didn't like the hump or "Glock knuckle" in terms of ergonomics, and I combined the "minus" connector and NY1 trigger spring along with a complete 25 cent trigger job (Dremel & Flitz) to go from a 6 pound staple gun feel to about a 9 pound DA revolver feel, and every Glock gets Ameriglo 3-dot night sights and some tacky grip tape panels (I like Galloway). That's just my preference. I prefer an easily-defended "Prosecution Exhibit A" if I ever find myself and My USCCA-funded defense attorney on the wrong side of the courtroom opposite some DA looking to up his stats before the next local judicial elections. With that in mind, I keep the G19 at home and carry the G43, so there's not even the homespun trigger job to explain once Castle Doctrine is out of play.

    But I love how full of a market we enjoy for tuning & tweeking Glock pistols. They're like the 10/22 of centerfire semi-auto handguns. I might prefer a custom 1911 for serious target sports if I shot in any, but it's great know I could spend the same money on aftermarket Glock parts and turn out a competitive race gun on the platform with which I'm already most familiar!

  4. There is one thing that a CCW gun must be able to do above everything else,go bang everytime you pull the trigger regardless whether it’s low end or high end ammo.My OEM GLOCK is 100% reliable and I personally see no need to spend hundreds of dollars to pimp it out and find out you have to have a pimped out bank account to feed it as well.If you can afford it and you are an avid reloader then knock yourself out.As for me,I like my stocky,blocky glocky just the way it is,100% reliable and all business.Just my two cents.

  5. I have a Glock 20 that has a 6″ KKM barrel, and a red dot sight. From 25 feet and a so-so rest, I recently put 10 consecutive 200 grain Nosler JHPs into a ragged hole 5/8th inch group. I called one of the shots slightly wide, so the group size should have been smaller. Powder charge was a healthy dose of Blue Dot. Thanks for the info about ammo quality and factory vs. aftermarket barrels.

  6. I bought a GLOCK 23 a decade ago When Dean Speir was hyping Ka Bangs. Bought a Federal .40 S&W barrel not because of Dean but because I had blundered and bought a .357 SIG GLOCK. The new barrel was beautifully rifled and grouped perfectly. Never regretted the change.

  7. I can shoot all my 45 ACP rounds, out of my Gen.1 Model 21, into a 25 cent piece hole at seven yards, offhand. Yes, I have thought about an aftermarket barrel, but if I want to shoot long distances with a handgun, I will use my Smith 586 6-inch or my 1911. I have shot competition for thirty years. I have competed against the Glock team (with a 17), and they came in 1, 2 3&4…I came in 5th. But, none of us other shooters saw the Glock team’s targets. That will always stick in my craw.
    My Glock is made for good accuracy at normal distances and reliability, that is what I use it for.
    The money would be better spent on ammo and practice.

  8. I bought some Maxx Tech 9mm once . . . once. I shot about 30 rounds and had to punch stuck cases out of my Walther three times in 30 rounds. I sold the remaining ammo and will never . . . read that, never buy that garbage again.

    As for Glock barrels, I’ll probably pick one threaded for a suppressor up for my G21 at some point, but a 4 pound trigger is all I’ve ever done to it for USPSA matches. Even without any additional work, it is a very accurate and totally reliable gun.

  9. great piece on the glock barrel swap. my g21 was an o.k. shooter until i installed a wilson combat barrel. now it’s a tack-driver. i was lucky; the barrel dropped in and worked as it was. it eats everything and is very accurate with ultramax lead ball ammo and everything else i’ve tried. my glock is my only .45 that will cycle cor-bon hollow points without a problem, too.

  10. Most people won’t see an appreciable difference in accuracy swapping out barrels, only do it to compete, shoot lead, or add a suppressor.

  11. No love for Barsto? I have fitted, match target Barsto barrels in all my Glocks.

    The fit is far superior to drop in barrels, and the accuracy is amazing.

  12. This explains why my 2 aftermarket barrels from different brands both shoot shotgun patterns 2.5″ high and right at 10 yards whereas my stock Glock barrel is dead nuts on with a ragged 1″ hole at 10 yards.

  13. I have KKM barrels in G19, G23, G29, G30S, G32 and G35 (357 Sig). They are excellent shooting Georgia Arms bulk FMJ practice rounds and more premium rounds. The 357 Sig G35 does under an inch at 25 just with the cheap GA practice Ammo. What he says about the 9mm is true and applies to the 40S&W. One other thing to mention that the barrels are fast with velocity and I had my G32’s Nitro Carbonized and picked up about 50 fps in the 357 Sig. I do not know if anyone has experienced this.