9mm Glock Case Support: Adequate or Not?

Whether a fan of Glock handguns or not, most agree that the Glock “KB” (“Ka Boom”) is a topic that is both enduring and widely-discussed on many firearm boards. Glock detractors frequent speak of inadequate chamber support, flawed gun design allowing the pistol to be fired with the barrel slightly out of battery to skyrocketing pressures from shooting non-jacketed lead bullets through the factory barrel’s polygonal bore (which Glock does advise against). Glock enthusiasts blame these KB’s on improperly loaded ammunition, defective factory cartridge cases if factory ammo was being used, and worn-out cases reloaded too many times if handloads were being fired. Improper reloads mistakenly stoked with too much powder is frequently cited as a possible cause, too. Who is right?

Though not as much in 9mm, the widely-used Glock pistol does suffer from the stigma of blown cases in what is called Glock “KABOOM’s” or “KB’s”. Is this something just inherent in the Glock design or might it be the product of other factors?

The first Glock KB’s that I personally witnessed were with a state-issued Glock 22. Texas’ Department of Wildlife had recently issued them to the state’s game wardens, one of whom was a friend of mine. He fired a few shots using brand new factory .40 S&W 180-gr. JHP’s before he got a KB. He was not hurt but the extractor left the gun as did the magazine. The case was still in the chamber and had blown along the extractor groove ahead of the rim. His pistol was repaired in short order and within few days he took it back to the range with the same issue-ammunition…and with the same result, another KABOOM! Damage was about the same but he was losing his enthusiasm to fire his Glock 22, and I admit declining his invitation to shoot it as well!) About this same time, a friend of mine bought one of the first 40-caliber Hi Powers to arrive at the local gun shop. He had not fired it but with a few days received a call from the gun shop owner advising him to call a specific number at Browning. He did so and was asked to return the pistol for a free “upgrade” which had mistakenly not been performed on his brand-new Hi Power. Though it was like pulling teeth, he eventually learned that the Hi Power barrel was to be replaced with one that had been given a little bit more barrel support in the chamber due to possible KB’s with but one brand of factory ammunition: Federal. This was the same brand being used by the game warden in his Glock 22. (It should be noted here that I am both a fan and user of Federal ammunition and that the problem with their earliest initial runs of the then-new .40 S&W appears corrected long ago. I have personally shot lots of it through many 40’s (Glocks and others) over the years with exactly zero problems. I do not know if Glock has increased chamber support in their 40-caliber barrels or not.

Though I didn’t witness it, a friend of mine reported a KB in his Glock 21. Neither he or nor I can blame it on the pistol. Seems he mistakenly left a cleaning swab in the barrel. Though a “low-pressure” cartridge compared to the .40, 9mm or .457 SIG, escaping gases around the trigger-area nearly severed his trigger finger. (He checks barrels before firing now for some reason!)

I saw a minor Glock KB in 9mm while a police firearm instructor. The department was using “remanufactured ammunition” (commercially reloaded) from an obscure company because of the price. I saw this 115-gr. ammunition blow and expel magazines from both a Glock 19 and a Beretta 92. I had no problems with it in a Browning Hi Power but still refused to personally shoot or issue it for practice after that. It could be that the Browning just took the ammunition in stride or more likely, I happened not to get one of the company’s inadvertent overloads by pure luck or chance! It is possible for brand new factory ammunition as well as factory reloaded rounds to be out of spec.

I thought that it might be worth the time and effort to compare the Glock 9mm barrel with other factory barrels and see if anything can be deduced. (I understand that 9mm is not the primary caliber in which Glock KB’s are being reported, but 9mm is the only caliber in which my Glocks are chambered, so it will have to do, at least for this initial report.)