The Gunperson's Authoritative Internet Information Resource.
The Gun Zone banner

Glock e-toolGlock kB! FAQ v1.35


Annotations regarding catastrophic failures in Glock pistols

Ruined Glock Frame

Annotation #1

Dean Speir and Frank James have reported that there are at least four discrete propagations of Accurate Arms #5 in the U.S.A., variously manufactured under the same label by IMI, Olin, Beta Chemical (Norinco) in China and, most recently, Lovex in Czechoslovakia.

Accurate Arms' most recent reloading guide contains the following statement regarding .40 S&W pistols and supported/unsupported cases:
"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 .40 S&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."
Hodgdon followed suit:
Warning: This data is intended for use in firearms with barrels which fully support the cartridge in the chamber. Use of this data in firearms which do not fully support the cartridge may result in bulged cases, ruptured cases, case head separation, or other condition which may result in damage to the firearm and/or result in injury or death of the shooter and/or bystanders.
Again, no names are mentioned, but the implication is clear that they're talkin' "Glock."

(See also Letters and this June 2006 report of a catastrophic Model 30 failure from Germany.)

Another source has identified VihtaVuori N350 as a potential problem. As a rule, you should always track lot numbers of your propellants, and when using a new lot (or to be even safer, a new canister), you should back off the power of your loads and slowly increase them until you have verified the safety of the new lot.
  • Don't use cast lead bullets at all, or at least be very careful about lead buildup if you do. (Glock, Inc. has finally stated this in their recent Glock Annuals.)
  • Religiously follow all the other safety precautions associated with normal reloading procedures. Take special care not to load a double charge.

Annotation #2

New Federal case failure 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, owned by Alliant Techsystems Inc. since December 2001, will address this for the record, it has been suggested that this move was dictated by the popularilty of the .40 S&W Glocks, and the munitions giant's attempt to hedge against a kB! with any of their ammunition.

Federal .40 S&W rounds which may contain suspect casings may be identified as follows:
  • Model 23 kB!Lot number consists of 10 characters (mostly numbers).
  • In the 7th position, there may be a number or a letter.
  • If there is a number in that position, the ammo was manufactured with the old style (possibly defective) brass.
  • If it contains the letter Y (1995) or R (1996), the ammo has the redesigned casing and should be okay.
  • If the letter H appears, then check the next three [3] digits (the last three in the lot number).
  • Ammo lot numbers H244 or below have the old style casings.
  • Lots H245 and above have the new style casings.
This information was provided by Federal Cartridge Company in September 1996.

Annotation #3

It was law enforcement/gunwriter Walt Rauch who first brought forth information that bullet set-back1 (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."
Repeated administrative chamberings can cause significant "set-back," even with Fereral's easy-feeding Hydra-shok. Excerpt of a 2 October 2000 response to Lt. Clyde Wason, Brea (CA) Police Department Rangemaster, by Sgt. Dean Caputo, Firearms Training Unit Rangemaster, Arcadia (CA) Police Department. Lt. Wason had requested information on the useful service life of duty ammunition.
"I found that the duty ammo took quite a beating in 6 months. Also just about every ammo manufacturer will tell you that the ammo is only rated for two (2) times through a semi-auto pistol (chambering/extracting), and both Winchester and Federal as recently as two months ago confirmed this again. After two times bullet set-back could start.

I can talk to you about bullet set-back... but let me just say that if you are using a .40 S&W caliber weapon, that tests have been conducted that show very little set-back has raised pressures around 60-70,000 psi (way above a proof load). This could cause, and has caused, weapon blow-ups in the .40."

Dean Caputo, Sgt. - FTU Rangemaster, Arcadia Police Department
Another example of "bullet set-back" Rauch published some specific information on this set-back issue in the May/June 2004 Police and Security News, in a feature entitled "Why Guns Blow Up!":
One last cause of "blowups:" The simple chambering and rechambering of a cartridge does push the bullet back into its case. Hirtenberg Ammunition Company of Austria (at the request of GLOCK, Inc.) determined that, with a .40 caliber cartridge, pushing the bullet back into the case 1/10 of an inch doubled the chamber pressure. This is higher than a proof load. This "push back" can occur with but one chambering since it is dependent on how well the case was crimped or sealed to the bullet. How many of us regularly chamber and rechamber the first two rounds of our carry loads? (Also, this chambering and ejecting chews up the case rim, which can cause a malfunction. If you are limited to how much ammo you are issued, after cycling the first two rounds a few times, strip the magazine and load these two rounds first so they are the last up in the stick.)
Broken feedramp following a catastrophic failure

Annotation #4

Most properly designed and well-maintained guns will not fire enough out of battery to expose enough of the cartridge's case web that it might be a factor in a kB! The Glocks, however, do... the pre-eminent pistolsmith Mike LaRocca of Worcester, Massachusetts and Dean Speir once gauged a Model 23 which would release the striker an entire quarter of an inch (0.250") out of battery, excessive even for a Glock.

Following that, a series of LE Glock-certified armorers tested a number of their service issue Models 19, and discovered some which were capable of firing at 0.125" (one-eight of an inch) or more out of battery... if you were in a John Farnam course with a 1911A1 pistol, and during his pre-flight armorer's test the hammer dropped with the slide cracked open an eighth of an inch, then Farnam would tell the student "go home and get another gun, fella, 'cause this one's unsafe on the line!"

Annotation #5

Courtesy of Clark Magnuson:
I recently bought a BarSto aftermarket barrel for a Glock 20 and made the following measurements:

My stock Glock 20 barrel leaves 0.306-inch of the case unsupported over the feed ramp.

My BarSto Glock 20 barrel leaves 0.224-inch of the case unsupported over the feed ramp.

The case web is 0.18-to-0.20-inch thick depending on how you measure it. That leaves at least 0.10" unsupported thin case wall in the stock barrel and 0.024-inch in the aftermarket BarSto barrel.
A comparison of Glock chambers: (L-R) 9 X 19mm, 357 SIG, .40 S&W
A comparison of the amount of casehead support in three different Glock chamberings, (left-right): 9 X 19mm, 357 SIG and .40 S&W. Surprisingly, the 357 SIG offers the fullest support of the three.

Annotation #6

At least one munitions manufacturer, MagSafe, has dared to openly cite Glock by name in a cautionary note:
  1. For greater safety and less wear on customer's guns, we now use .38 Special +P nickel brass for the .38 MAX, & Triton's .45 Super brass for the .45 MAX and .45 Super SWAT Loads. Glock 45s have huge throats; be careful.
The Glock kB! FAQ has been a joint project by:
Dean Speir, Jay L. Swan and Todd Louis Green, with
significant contributions from R. Walter Rauch and Frank James
Post questions or comments in The Gun Zone Forum.
© 2000-2007 by
The Gun Zone
All Rights Reserved.
Woolrich Elite Series TacticalTM is a Backyard Outfitter Exclusive.

This page, as with all pages in The Gun Zone, was designed with CSS, and displays at its best in a CSS1-compliant browser... which, sad to relate, yours is not. However, while much of the formatting may be "lost," due to the wonderful properties of CSS, this document should still be readable.