A Brief Primer on KB's

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

  1. cw2go

    I can't agree with the original post. It's not a primer. And it misses the key points.

    The real problem is that you can fire many Glocks slightly out-of-battery -- especially earlier models, like mine. Combine this with the unsupported chamber in the feed ramp area, and you are left with a blackened, stinging hand, a look of shock on your face, and wondering what the hell just happened, and why your magazine became a projectile. (Fortunately only the mag.) I wasn't really injured, and my G19 survived with a new slide release, mag release, and mag, and has had another 1 - 2,000 rds though it. But it was clear from the undertone of my discussion with the nice lady at Glock that this was not an uncommon thing, even with 9s, and that they don't really think you should be shooting reloads or Federal ammo. These were the only reloads it ever shot, and it blew before I had 20 rds of reloads through it (commercial reloads, not home brew). I won't be shooting reloads, plated slugs, or Federal ever again.

    And I do think Glock should be seriously faulted for failing to call its "upgrade" a "recall", which would have saved quite a few of us the aforementioned stinging hand and damaged parts replacement. A proper warning, and a note about the "upgrade" would have been appropriate. This was not responsible corporate behavior.

    So I see three key issues:
    1. ability to fire out of full lockup
    2. excessive unsupported chamber area
    3. failure to notify the customer base of the need to get the parts upgrade

    Add to this a fourth item, like a lead shaving, oversize case, dirty chamber, insufficient force chambering the first round -- anything which causes incomplete lockup -- NOW you have a Kb!

    Just my opinion, but one that is now obvious to me, and I'm sticking to it.

    -- cw

    Wanna kill these ads? We can help!
  2. What are the details on the "Upgrade" and how does one get it?

  3. Glock has a had a few parts upgrades.At one time they were even machining 45 and 10mm slide(and maybe others)at the extractor.The parts upgrades are still there but I think they stopped the slide machining.The biggest "upgrade" that should have been a recall is most of the frames with serial numbers beginning with "E" with three letters have faulty rails.Glock will replace the frame if it is on the defective rail list or if the rails have broken.
  4. Very helpful, thanks.
  5. how can this happen?

    If the slide moves back even a little, the trigger no longer operates the striker.
    This happens long before the slide to barrel "opers"...
  6. cw2go

    It doesn't have to be far from full lockup to make a big difference. My Glock 19 appears to be able to fire over 1/16-inch from lockup (enough for the barrel to fall noticeably, perhaps 1/32-inch or better), but it will not fire with 1/8-inch slide retraction. Hopefully, the upgrade kit will reduce this. You can test your own, retracting the slide just slightly to see at what point it you can pull the trigger and where it gets blocked. I have not installed the upgrade yet to see what the effect is, but only the old Glocks need it -- as I understand it, all those built in the last decade or so do not, and models after the 24.

    Information on the upgrade kit (and which s/ns need it) can be found at: http://www.thegunzone.com/glock/upgrade-faq.html

    My writeup and photos on the kB! were posted at: http://www.thegunzone.com/glock/g19-kb.html

    The Glock kB! FAQ can be found at http://www.thegunzone.com/glock/glock-kb-faq.html -- there is a lot of info there.

    -- cw

  7. we may differ on what we mean by "lockup"
    when you move the slide back by 1/16,isn't the barrel still tight against the breech?
  8. i have EVT143, do you think i should request for a new frame from glock? thanks
  9. cw2go

    By full lockup, I mean locking surfaces fully and completely engaged as required to take the full design pressure of normal firing, plus the design safety margin (which should handle significant overpressure for proof firing). At 1/16" back, it is close to lockup, but has just started disengaging (which I suspect is significant), and you can still pull the trigger, so you could conceivably get a kB! in that condition.

    The most common kB! is not a failure of the barrel, slide, or frame, but a case failure in the unsupported area at the feed ramp, which is obvious if you examine a failed case or check out the pictures. (This differs from the original post here, which defines kB! in a manner contrary to that of the person who defined the term, who'se site URL I posted above.)

    You can test your own pistol (AFTER confirming it is unloaded) by gently pressing back the slide and verifying where it reaches the point where you can no longer get the trigger to release. Once I get the upgrade kit installed (which includes 6 parts: a new Extractor, Spring-loaded bearing, Firing pin safety and spring, Firing pin / striker, Trigger bar) I will run the test again to see if reductes the distance above.

    -- cw
  10. Tboh

    Could I ask a basic Q here?

    What is the carry round that has the lease problems. Least chance of KB, Miss feed, FTE, SSS and anything else that'll likely run into as a CCW.

    .40 and 9mm in G23 in hand and possibly a G26 or 27 shortly.

    Has anyone figured it out?
  11. cw2go

    Least reported problems appear to be the 9mm models, which would be expected since they were designed to pass tough military acceptance trials, and they've had the longest production runs. But it has to do more with what ammo you shoot than anything else. As a CCW, I'd stick to known factory loads, and you should be fine with any caliber. And run about a case (500 rds) through it, maybe in IPSC, before you give it the thumbs up.

    -- cw
  12. In a perfect world the design would not allow an "out of battery" firing. However, all mechanical devices can get out of alignment, suffer wear, malfunction, defect or failure.;g
  13. Perhaps - but have you actually seen that happen?

    I did a test with a 10mm case in my glock 35.

    I trimmed the case little by little.

    I could never get the trigger to function UNLESS the breech was tight against the barrel.

    The example listed in the URL is described by the poster as a simple case failure - and was attributed by the poster due to overpressure reloads. That's not a gun failure.
  14. I think that you pinpointed the key issue - though with Walter gone, I am only interpreting his post.

    I am sure that as you state he intended KBs to mean only the barrel/slide failures - case failures are (under this definition not KBs, but rather ammo failures)...

    Regarding the "out of battery" experiences, the high speed photos that I've seen show the bullets leaving the barrel (and I assume pressure falling to near zero) before there is any movement of the slide relative to the frame and barrel.

    This is why I feel that if the breech is tight against the barrel then the slight backward downward movement that is possible is not significant.

    From my reading of your URL reference, it seems thit you too attribute the failure to be due to ammo overpressure.
  15. Correct for one of the URLs, but one does deal with out of battery.

    Yes, I have had it happen.(non Glock). It is now "retired" because it was too old and not worth the repair cost. It sounds like your gun is working the way it was designed to work. So do my "active" guns. I really like my Glock products.:)

    My point is that we need to check our equipment regularly to make sure it is in proper working order. [Like checking the brakes on your car]If your equipment is not working properly then get it fixed or retire it.
  16. ok - thanks for that data point...
  17. cw2go

    First, I was the poster, so I know exactly what the writeup says, and what all the evidence looks like, since I still have it. It is possible that there was some overpressure (impossible to say for sure), but that was not likely to cause the kB! -- it was most likely a slight out-of-battery condition. This is not a "simple case failure". The case is not designed to contain that level of pressure without support. It is a combination of several elements, the most critical are the ability to fire slightly out-of-battery (i.e.- short of full lockup) combined with a partially unsupported chamber. If the pressure was high, then that may also have been a contributing factor. If I were to rewrite the linked post about the G19 kB! (since I was the orignal author), I would more clearly characterize it as a slightly out-of-battery discharge, as this is where the evidence points. It is important that owners of the earlier models understand there is an upgrade kit to avoid this condition. If you have an early model (as listed in the link), get the upgrade!!

    As for the attempt of several apologists to redefine kB! as *only* an event that completely blows up the firearm is particularly inappropriate. That is NOT the definition of kB! Attempting to redefine away is an inappropriate way to address the problem, especially when it is avoidable. That's like having a doctor who tells you it isn't cancer unless it kills you, so don't worry about it. The term kB! was coined by Dean Speir, and he calls this a kB!, so I will stick with his definition, not that of some revisionist.

    For those worried about the problem, read the linked acticle (above) about the upgrade kit and find out if your model needs it. Glock should have called it a recall and gotten the word out, but they didn't. Even without the upgrade, you will be okay if you avoid reloads, lead, plated slugs, and Federal cases (unless you really know what you are doing, or like taking chances). Do this and you will not have a problem. This sure beats wringing your hands and wondering if you are okay.

    If you do experience a kB!, please share the detailed info so we are all kept informed, and make sure you report it to Glock and the ammo manufacturer, and one of them will take care of the parts and repairs.

    -- cw
  18. Sorry for misinterpreting what you had written -

    Here is the part of your URL post that made me term it a simple case failure - I note that you use the term "classic" rather than "simple" - my apologies.
    Examination of the Glock and case show it to be a classic case failure kB!

    Here is the part that made me suspect the ammo.
    This commercial "reload" from a local firm was one of only 17 or so reloaded rounds ever fired through this pistol and examination of the primer showed a greater-than-expected flattening effect and engraving of primer metal, with a slight extrusion into the primer pin recess....

    Regarding whether the cause was out of battery or overpressure:

    We know that there were signs of overpressure per your post.

    We also know that other rounds in this batch showed over pressure - again per your post.

    We also know that Glocks do not fully support the case - per your references and many others.

    We also know from your photos that the case failure occured ONLY in the unsupported area and not all the way around the case.

    What I don't know is why you go from the above data to your opinion that
    "...it was most likely a slight out-of-battery condition."

    I will restate my reasons for disbelief in
    "out of battery experiences" -
    1) Though the trigger on a glock CAN activate the striker when the barrel is pushed slightly down and back, THE BREECH IS STILL TIGHT against the barrel and bullet.
    2) all high speed photos of pistol bullets, that I have seen exiting a barrel have thus far always shown the bullet exiting the barrel BEFORE the slide-barrel begins to move relative to the frame. Any contrary photo would be very welcome.

    Regarding whether to use Dean Speir's definition of KB rather than Walter's

    I appreciate the argument that since Dean coined the term, it should mean exactly what he meant it to mean (sort of like the Cheshire cat in Alice)...

    But, I also appreciate that language evolves, and I think that Walter was attempting to draw a clarifing distinction between different types of failures.
  19. Vincep

    Vincep Messin with 99

  20. JSOO

    Pardon my ignorance here as I am new to the technical side of shooting but just what is a KB?

Similar Threads Forum Date
A brief primer for jail/prison sentences Cop Talk Apr 24, 2013
One man's brief and brutally honest take on Glock vs. M&P General Firearms Forum Aug 13, 2015
Beckley, WV 2015 Debriefing & Photo Thread! GSSF Aug 8, 2015
Marietta, OH 2015 Debriefing & Photo Thread GSSF Jul 25, 2015
Dawsonville 2015 Debrief GSSF Jul 12, 2015

Share This Page

Duty Gear at CopsPlus