|ZEV Dimpled Barrel|
Should I Upgrade my 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!
|Glock 19 Upgraded - Deus Ex Machina trigger, PWS billet slide, Trijicon sights, KKM barrel, and Vickers slide & mag release all riding on a limited edition tan frame.|
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.
WHAT’S THE BIG DEAL WITH AFTERMARKET MATCH BARRELS?
Aftermarket “Match grade” barrels such as ZEV and KKM dimensionally have a tighter fit than the Glock barrels which 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 later 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 toleranced 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.
A WORKING EXAMPLE OF ACCURACY
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 and don't sell your stock barrel.
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. Personally I carry a factory Glock barrel now in the above pictured G19. So there you have it, if you can swing shooting top and 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 are kidding yourself that the upgrade with deliver better accuracy.
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Hornady - http://www.hornady.com
Speer - http://www.speer-bullets.com