version 1.04, 14 March 98
Dean Speir (DeanSpeir@prodigy.com)
Jay L. Swan (firstname.lastname@example.org)
Todd Louis Green (email@example.com)
with significant contributions from
Walt Rauch (WalterRauch1@compuserve.com)
[the views expressed herein do not necessarily reflect those of .40something or The Glock Papers]
The Glock kB! FAQ
|1. What is a kB!?||Coined by firearms journalist Dean
Speir, "kB!" is shorthand for kaBOOM!, which is the written representation of
what happens when one has a catastrophic explosive event in one's firearm, or, for the
purposes of this FAQ, one's Glock.
|2. What causes a kB!?||Catastrophic failures may be caused by a
variety of problems, but in general a Glock kB! is as a result of a case failure.
The case failure occurs when pressure inside the cartridge increases to the point that it cannot be contained by the case and the material of the case fails, allowing hot gases to escape from the ruptured case web at damagingly high velocities.
The resulting uncontained forces can blow the magazine out of the gun, emulsify the locking block, cause the tip of the trigger to be snipped off, ruin the trigger bar, rupture the barrel, peel the forward edge of the slide at the ejection port up, and do other nasty things. In general, Glocks tend to contain case failures fairly well, but under some circumstances they can cause injury as well as damage to one's gun. At least one LEO has been injured in a kB! involving a Glock 21 and a Winchester factory overcharge.
Additionally, there is some evidence of there being another cause of a kB!... a barrel failure caused by improper metallurgy.
|3. Which Glock models are affected?||Speir has documented many instances of
kB!s, all of them in the Models 20-something Glock (.40 S&W, 10mm and .45 ACP). Speir
has no confirmed cases of Glock kB!s in the 9 x 19mm (Models 17, 17L, 18,
19 and 26) or the .380 ACP/9 X 17mm (Models 25 and 28).
|4. Why does a kB! occur in these Glock models?||Reports compiled by Speir from various
independent laboratories are inconclusive as to one single cause for the catastrophic
There do, however, appear to be several contributing factors which collectively may induce catastrophic case failures:
|5. Do kB!s occur in other guns or just Glocks?||kB!s do, of course, occur in other guns,
but no one appears to be keeping accurate statistics for most of them. Many 1911-style
handguns have partially unsupported case mouths, and numerous case separations have
occurred in these guns. Early .38 Super barrels were particularly susceptible. Gunwriter
Frank James has documented a number of kB!s in HK USP .40 pistols, which do have
fully supported chambers.
|6. What is the relationship between reloads and kB!s||Most kB!s occur with commercially
remanufactured or personally reloaded ammunition.
Successive re-sizing and firing of a case result in eventual weakening of the brass, increasing the probability of case failure. The partially unsupported chamber in the Glock exacerbates this problem.
"Hard crimping" or overseating of bullets, particularly in the .40 S&W, can cause dramatic increases in pressure almost to the same degree as a propellant overcharge. [See Annotation #3] Either alone or in combination with a weakened case, these factors can result in a kB!
Some people have also postulated a relationship between the use of cast lead bullets and kB!, arguing that buildup of lead in the chamber can lead to pressure buildups as well. The jury seems to be out on this one as a direct causation, but lead build-up will sometimes cause a round to not fully chamber, and as Glocks can discharge with the action not completely locked up ("out of battery"), this can lead to a catastrophic failure.
|7. What can I do to prevent a kB!?||
At an October 1996 G.S.S.F. match, one competitor with a Model 22 had simply switched to a .40 S&W Sigma barrel which he averred not only better allowed him to shoot lead because of the conventional rifling, but that the fully supported Sigma chamber significantly decreased the opportunities for a kB! Note: This procedure is neither recommended nor authorized.
|8. If I insist on reloading for my 20-something Glock anyway, what can I do to minimize the chance of a kB!?||
|Annotation #1||Accurate Arms' current reloading guide
contains the following statement regarding .40 S&W pistols and supported/unsupported
"In recent years it has become very apparent that there exists a situation regarding some pistols chambered for the .40 S&W cartridge. Some of the pistols currently available to shooters may not provide complete support to the case when a cartridge is chambered."
"This information [AA's load data] is safe for use in firearms which provide complete support of the case. Failure to fully support the case with cartridges of such intensity may result in bulged cases, ruptured cases, separated case heads or other consequences which may result in damage to the firearm and/or injury or death to the shooter and/or bystanders."
"If you own a firearm chambered for the .40 S&W, we recommend you contact the manufacturer to determine if the case is fully supported."
"If your firearm does not provide complete support for the case, DO NOT USE Accurate Arms Company data or products to reload your .40S&W ammunition."
"This is the first time Accurate Arms Company has felt it necessary to place such a restriction on the use of our products, but the continued safety and welfare of the shooting public compels us to do so."
|Annotation #2||In late 1995, Federal Cartridge of
Anoka, Minnesota quietly undertook a redesign of their .40 S&W cartridge case to
strengthen internally the area of the case web. While no one at Federal will address this
for the record, it has been suggested that this move was dictated by the popularity of the
.40 S&W Glocks, and the munitions giant's attempt to hedge against a kB! with any of
Federal .40 S&W rounds which may contain suspect casings may be identified as follows:
This information was provided by Federal Cartridge Company in September 1996.
|Annotation #3||It was Law Enforcement/Gun writer Walt
Rauch who first brought forth information that bullet set-back (such as often occurs in
administrative unloading/loading) in the .40 S&W could raise pressures exponentially.
"This was first confirmed via a European cartridge maker (Hirtenberger In Austria) from information given to me by a high level Glock representative. 1/10" set back can cause pressures to double from 35,000 psi to 70,000 psi.
"Note this was achieved with factory ammo and without the detrimental effect of lead build up in the barrels. I also had 'off the record' confirmations of this from two U.S. sources, one governmental and one manufacturer."
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