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A Brief Primer on KB's

Discussion in 'Valuable Info' started by WalterGA, Sep 6, 2004.

  1. WalterGA

    WalterGA Millennium Member

    Jan 26, 1999
    The purpose of this thread isn't to be contentious relative to this frequently misunderstood subject, but rather to offer a little rational thought and a few facts. (Particularly for the newbies who might have been influenced by the Internet Ignorami)

    First, whether a pistol, eg., Glock, has a supported or unsupported chamber is generally irrelevant to the subject of KB's. While an unsupported chamber might contribute to a case failure, a case failure does not constitute a KB.

    So, what's a KB, then? Well, to me, a KB results in catastrophic failure of either a pistol's barrel or slide, or both. A case failure will probably result in a damaged mag, mag release, trigger assembly, maybe even a damaged frame. (or, in the case of 1911's, shattered grips)

    In order for a case failure @ 6 o'clock to cause a KB, one would have to accept the premise that such a failure would cause dramatic increases in chamber pressure. Does anybody really believe that a RELEASE of pressure @ 6 o'clock will increase chamber pressure? Ever take h.s. physics? If not, or if you failed h.s. physics, then perhaps you should try writing for a gunrag or sponsoring a specious internet site.

    Let's use an analogy for the purposes of demonstrating the silliness of blaming lack of case support for KB's. Ever fill up an air tank? Ever wonder what happens to a steam boiler or water heater when tank pressures exceed the tanks' pressure maximums? Well, if the tank has a pop-off valve or other method of releasing pressure, not much happens. With no such relief mechanism, a lot happens, catastrophically. Get the analogy with pistol chambers? If you don't, then, well, good luck with your life.

    Photos of blown-up pistols on websites prove nothing, nor make any statements about the design features of that particular blown-up pistol. The picture might just reflect the statistical quality control anomaly of a factory round, or it might indicate an overcharged reload. The posting of a picture or anecdote on the internet doesn't give one any facts at all regarding KB's. (Even if the photos are of G21's blown up by police officers)

    There are, I believe, over 2 million Glocks alive and well worldwide. If, as is claimed by the uninformed, Glock's design causes Glocks to randomly explode, then we'd certainly be hearing of more than just a few random cases of exploded Glocks on the internet. Nope, if design flaws were the problem, we'd be seeing tens of thousands of blown-up Glocks, government-demanded recalls, and not just the few "examples" that are posted here-and-there.

    Now for my own anecdote. I've fired somewhere in the vicinity of 150,000 rounds of my reloads through my Glocks, mostly through G21's. Matt, of CGR, and others, have fired many times more of their reloads through their Glocks than I have through mine. I reload my .45ACP's until the necks split. I've never even had a 6 o'clock case failure, let alone a KB, using a factory Glock barrel.

    I did experience a KB with my original G21 (see photo), using an aftermarket barrel, powder that was too fast, bullet that was too heavy, and a little of my own carelessness mixed in. Clearly had a feedramp bullet setback, with the expected KB. Please note that the case is split down its entire length. If this had been a 6 o'clock blowout, the case would only have failed @ 6 o'clock.

    Glocks are among the safest pistols in use today. They are not subject to an abnormal risk of KB. If you overcharge, or, especially, doublecharge a round or use an overcharged or doublecharged factory round, your pistol, regardless of manufacturer, will probably KB.

    It's as simple as that.
  2. fabricator

    fabricator Got Biodiesel?

    Aug 28, 2003
    Grand Haven, MI
    Hey! Eddie, Fred or Mark, this really needs to be stickied.

  3. pwharve


    May 23, 2004
    I second the motion.
  4. G36's Rule

    G36's Rule Senior Member

    Dec 1, 2001
    Spring, TX.
    Excellent post Walter. Needs to be a sticky.
  5. Medpilot 2

    Medpilot 2 Smkumifyagotum

    Oct 10, 2003
    That makes sense to me.:)
  6. Guest

    You da man, Walter!!

    Third (or forth) the sticky (but you know the question will still get axed.....
  7. Yes! After ignition (primer) the overdose of powder or bullet setback creates a moment of catastrophic shock wave that does not expell the bullet from the casing fast enough to releive the vessle (case) of its pressure caused by immediate expelling of burning gasses.

    The case ruptures.Shockwave continues through the frame and components until containment by the frame is diminished, and hot gasses exit through any and all frame holes either built in or newly created by shockwave.

    Glock 21(in your case) flies unnaturally from fist, shooting partner says: Hey man what the **** are you tossing YOUR 21 arround for!

    You double over in pain and count fingers. If you are lucky you count five and no hospital visit is needed.

    The next thing you begin is the denial process, or the now I know process.:soap:
  8. striderglock

    striderglock HVACR

    Aug 24, 2002
    Excellent post! Needs to be sticky!
  9. BuffaloBo


    Jun 22, 2004
    Your own definition of a "KB" is admittedly subjective. I don't care if it's a case failure, a 6 o'clock failure, an overloaded powder charge, wrong bullet choice or whatever. I'll still consider it a "KB" or whatever you want to call it because the gun and/or components fail consequentially.

    I'll agree that Glocks are no more or no less prone to "KB's" then other quality handguns, however.

    Maybe we need to rename automobile collisions accordingly to suit the circumstances of their causes?
  10. Metric


    Sep 9, 2003
    Since everyone else is demanding that this post be framed and mounted, I suppose I should say a couple of things "for the sake of argument."

    The above quote looks a bit to me like defining terminology in such a way that the term "KB" becomes non-useful. Of course, the fact may remain that a particular gun (say, for example, a Glock) is very prone to "case failure" (due to a lack of chamber support inherent in the design) which involves a loud noise sounding roughly like "kabooom" and perhaps permanent damage to the gun -- yet we're not allowed to call it a "KB" because it doesn't meet Walter's definition unless the barrel has been torn apart.

    Assuming we use the "blown barrel" definition of "KB" -- it does not follow that all barrels are equally likely to spit, given a particular overcharge. Glocks may be more or less prone to this particular brand of catastrophic failure -- we simply do not have any solid data to compare, here (if I am ignorant on this point, please enlighten me). All we have is a message board that seems to see more than its share of "I saw a KB at the range today" threads on a regular basis.
  11. WalterGA

    WalterGA Millennium Member

    Jan 26, 1999
    Excellent demonstration of non sequitur. Thanks for the contribution. ;)
  12. jupiter


    Aug 9, 2002
    North Mississippi
    I have been reloading for many years.
    I have NEVER had any kind of KB except with a Glock!
    I've seen glocks have what I call a Kb at least 4 times.
    Twice it only blew the Mag out of the bottom of the gun.
    Another time it blew the Mag out and the Extractor into nowhere land.
    Another time at a Match where I didn't see the total outcome of what happened.
    Just because The whole thing didn't explode does not mean it didn't have a KB in my eyes.
    That Extractor that went into NOWHERE land could have just as easily
    come back in my face.
    There are far too many stories about Glock Kbs to just write it off
    and disgard anything that didn't blow the barrel and slide to hell as not being a serious problem. Glock will tell you the kbs with happen because of reloading cast bullets with the hexagonal rifling.
    I had a Barsto Barrel in my 34.
    The bottom line for the Average shooter is to STAY away from ANY Reloaded Ammo. Also Stay away from the AMERC Crap.

    With that said, I feel if you use good ammo, you will never have a problem with a glock.
    I carry my 23 every day and not because I have to.
    I have Sigs, HKs, Kimbers etc,etc,etc.
    I feel like the glock is just about as quick out of the holster and
    able to put good shots on targets as fast as any gun every made.
  13. Metric


    Sep 9, 2003
    To reiterate my non sequitur, you have defined a "KB" in such a way that most people will never see one. That doesn't change the fact that an unusually large number of people experience catastrophic failure, due in part to unsupported chambers, and report them here on this message board.

    I suppose one of us should mention "Solomon juice" at this point, right?
  14. pwharve


    May 23, 2004
    Definitions of KB not widthstanding, I still think this thread is worth the while.

    Anecdotes about what pistols a particular person has KBed or not are not all that useful in the grand scheme of 10s of millions of pistols in use world wide. Does anyone deny that other pistols will KB, or other weapons in general? I've seen two, one was mine in a T/C Benchmark--fired out of battery.

    The big thing I see the anti-Glock crowd bringing up is the lack of full case support. However, in one of the examples used above, the KB occured in a BarSto barrel--I thought those were reamed to SAAMI specs or tighter. So, doesn't that remove the lack of full case support as a factor in KB? Do the BarSto barrels still lack a fully supported chamber? If so, why? I'm looking to learn here.

    And, if they are KB prone, why do you people who have KBed them keep using them?

    How much of this is internet megaphone? Remember the internet and the tendency for lemmingism (and I'm NOT accusing anyone here of that--I'm not questionin anyone's bona fides) brought us all of those stupid send me a card e-mails and the thought that Target is owned by France.

    Where are the statistics on the numbers of KB per unit? Or, alternatively, numbers of KB lawsuits per unit. AT the rate some people suggest Glocks KB, it would seem to me that Glock would be bankrupt. What are the statistics for KB in the militaries that have them in service? Militaries being what they are, I'm sure they keep records like we do.

    Same goes for the G19 issue. I don't doubt one exists. Some percentage of pistols aren't working properly, this is a shame and something Glock should be investigating. I hope the return to standard mags resolves the problem forever. But, it is a percentage, and from what I can gather from my local dealers who sell the things, its not the majority percentage--they just don't get them back with complaints. One dealer hadn't even heard there was a problem, and he sells bunches of them. Mine isn't one of the ones with a problem, so far, and yes, I've tried all sorts of JHP. We'll see what shakes out over time.

    I think cultism toward anything is pretty silly, Glocks included, but of all the well documented evidence I've been able to get my hands on leads me to believe that the internet anti-Glock megaphone is working well.

  15. Guest

    My own experience with a G22 and my early .40 reloads - I was loading 180 FMJ over AA5 powder (I forget the charge weight now). My wife was shooting my G22, and out of the corner of my eye I saw a flash larger than normal, not coming from the muzzle, but from the middle of the pistol, right behind the breech area.

    As I got to her and checked her for damage (none!), I saw that the mag & backstrap plug had been ejected, slide stop sheared off and the slide was locked up tight (had to bang it against an I beam to break it loose!).

    Chamber area had cracks on both sides with the case head blown out at the 6:00 (the dreaded unsupported area) and no primer in the case. Did not get the 'classic' barrel peel, though ;f

    I believe what happened was bullet set-back creating a pressure spike. At first, I though kB (actually, more like OC ;f ), but gradually moved away from that explanation and have settled on set-back.

    I have long since changed my reloading habits and no longer use 180gr bullets or that fast a powder in 40. I still carry that same G22 (obviously fixed since then), and have shot many hundreds, if not thousands of my reloads through it (with an aftermarket barrel) and my G35 with factory barrel. Not as many of my reloads thru a G27 & G23 with factory barrels with no ill effects.

    I firmly believe, but have no real desire to test that belief, that even with a "fully supported chamber", the same thing would have happened, though maybe not the blow-out at 6.
  16. Guest

    case head
  17. Guest

    left side
  18. BuffaloBo


    Jun 22, 2004

    How long ago did this happen?
    The reason why I ask is because I noticed that the case was a Federal. I heard or read somewhere that there might have been some issues with Federal cases being a little flimsy and were prone to blowouts. Also, I heard that they quietly fixed these deficiencies since then. BTW I load Federal cases in .40 these days with no apprehension.
  19. I like this definition since it clearly separates the case failure from the barrel slide failure.

    If only it had been the original definition.

    I doubt it will become common usage since the colloquial definition seems to be any type of damaging explosive incident.

    I think we are doomed to have KB continue to "mean" both a case failure and a barrel/slide failure.

    In any event, the unsupported chamber actually becomes a "relief valve" type of safety feature since it allows a less expensive failure to occur - the case rupture - rather than a Barrel/Slide failure. In this sense it acts much like the pressure relief valve in your steam boiler analogy.

    I note from your past postings that you won't own/shoot .40 s&w -
    Is it possible that .40s&w in the glock (based on the earlier 9mm slide constraints) has a thinner barrel/chamber than other .40s&w and therefore may be slightly more prone to the Barrel/Slide failure you call a KB?
    Or is there some other reason for objecting to the .40s&w?

    Thanks for the clear and well intentioned post.
    I doubt you'll change the meaning of KB, but the discussion may help clarify the issues.