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The Glock kB! FAQ - Version 1.0c

Compiled by Jay Swan, with help from Dean Speir
and other Glock-L members

1. What is a kB!?
2. What causes a kB!?
3. Which Glock models are affected?
4. Why does a kB! occur in these Glock models?
5. Do kB!'s occur in other guns or just Glocks?
6. What is the relationship between reloads and kB!s?
7. What can I do to prevent a kB!?
8. If I insist on reloading for my 20-something Glock anyway,
   what can I do to minimize the chance of a kB!?

1. What is a kB!?

"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 contain case failures fairly well, but under some circumstances they can cause injury as well as damage to one's gun. At least one police officer has been injured in a kB! involving a Glock 21 and a Winchester factory overcharge.

3. Which Glock models are affected?

Glock-L member and firearms journalist Dean 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 kB!s in the 9 x 19mm Glocks (Models 17, 17L, 18, 19 and 26).

4. Why do kB!s occur in these Glock models?

Reports compiled by Speir from various independent laboratories are inconclusive as to one single cause for the catastrophic failures.

There do, however, appear to be several contributing factors which may induce catastrophic case failures:

1. Firing out of battery. Most Glocks will do this to some degree, especially those improperly maintained.
   
   
2. Significantly overpressure rounds. These occur mostly in homemade reloads or in commerically remanufactured ammunition, but have occured in factory ammunition as well.
   
   
3. The lack of full case support in the critical area over the feed ramp of all large caliber (.40 S&W, 10mm, .45 ACP) Glock pistols.
   
   Ostensibly as a measure to promote feed reliability, Glock chamber mouths are slightly oversized. One can test this by removing the barrel from the Glock, dropping a factory round into the chamber, and observing that there is brass exposed at the six o'clock position. Take a fired case and note that there is a slight engraving if not actual bulge around the case web, which is most pronounced in the area of the case which, upon firing, was in the six-o'clock position.
   
   
4. The use of personally reloaded or commercially remanufactured ammunition utilizing cartridge cases of indeterminable generation.
   
   Unlike many rifle handloaders, many of those who reload for handguns do not as a habit separate their fired cases by generation, and each time a case is re-sized and reloaded, the brass "works" and weakens.
   
   kB!'s have been documented with factory ammunition, but most of them occur with either commerical or homemade reloads.

5. Do kB!'s occur in other guns or just in Glocks?

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 firings 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. 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!s, 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 chamber fully, and as Glocks can discharge with the action not completely locked up, this can lead to a catastrophic failure.

7. What can I do to prevent a kB!?

1. Shoot only new factory ammunition out of your Glock. This is what Glock, Inc. recommends, as do several members of Glock-L. Shooting reloads voids your factory warranty.
   
   
2. Buy a custom barrel with a fully supported chamber. Makers include Bar-Sto (barsto@earthlink.net), Jarvis, Wilson (wilsoncb@yournet.com), and Briley (http://rampages.onramp.net/~briley).
   
   

8. If I insist on reloading for my .40-something Glock, what can I do to minimize the chances of a kB!?

1. Buy a custom barrel. See 6B.
   
   
2. Keep careful track of your brass. Load "Major Power Factor" loads only in new brass. Don't use range pickups. Don't shoot "hot loads" from used brass. Discard used brass sooner than you would normally.
   
   
3. Use calipers or case gauges to keep your reloads within spec. Check for excessive bulging in the case web and make sure your bullets are seated to the correct length. Also check for excessive case thinning or bulging.
   
   
4. The propellant AA#5 has been identified in a disproportionate number of kB!s, not only in Glocks but USP40s with barrels which do provide full case support. A number of Glock-L members have reported kB!'s involving this propellant. It is not clear whether these kB!'s are the fault of the propellant or the reloader, but it is clear that they are occuring in disproportionate numbers.
   
   Dean Speir has reported that there are a number of propagations of AA#5 in the United States, variously manufactured under the same label by IMI, Olin and resources in China and Chechoslovakia.
   
   As a rule, you should always track the lot numbers of your propellants, and when using a new lot (or to be even safer, a new cannister), you should back off the power of your loads and slowly increase them until you have verified the safety of the new lot.
   
   
5. Don't use cast lead bullets at all, or at least be very careful about lead buildup if you do.
   
   
6. Religiously follow all the other safety precautions associated with normal reloading procedures. Take special care not to load a double charge.

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