What causes Glock kabooms?

[WestKentucky]

Really simple question, likely going to be some argument, but there is a purpose here which I will refrain from posting until later because I feel it would cause friction on a thread I want to be free.

So what causes most of the kabooms in a Glock? Is pressure often an issue? Slide velocity/battering causing damage/failure? Out of battery primer strikes? And most importantly, are the kabooms something that could be avoided by selecting better/different parts.

 

[NIGHTLORD40K]

Hm, AFAIK most blowed up Glocks were early .40s which had an insufficiently supported feed ramp. This, coupled with cheap brass, resulted in some ruptured cases and kabooms.

 

[crestoncowboy]

Most ive seen were reloaded ammo in early gen 1 or 2 sloppy chambers (gen 1 were all 9mm and they did it too) . Glock bulge was a real thing I assure you. Ive shot gen 3 glocks for many years, more rounds than most will ever think of and ive had no problem even with handloads. Only guns I've personally seen kaboom were revolvers and one HK myself.
Usually the revolvers are from top strap flame cutting. Most semi autos are from squib loads. From what I've seen. Vast majority of the ones I've read about and all that I've seen were handloads. But I'm no expert
I have ruptured cases in factory ammo as but the guns survived so no kaboom really. Just bad brass. (Armscorp)

 

[Obturation]

Improper ammunition as far as I know. A properly maintained gun with good ammo generally won't kaboom. As with most manufactures , glock doesn't recommend reloads- integrity of used brass and assembly of unknown (to them) components is outside of their control .

 

[bearcreek]

So what causes most of the kabooms in a Glock? Is pressure often an issue? Slide velocity/battering causing damage/failure? Out of battery primer strikes?

Same thing that causes most of them with any other semi auto (or any decent quality gun). Bad ammo.

And most importantly, are the kabooms something that could be avoided by selecting better/different parts.

Generally speaking, probably not, since it's usually bad ammo, not a bad gun.

 

[243winxb]

Early models had unsupported chambers/ barrel. The high pressure 40 S&W didnt like unsupported. The Hodgdon website even had a warning not to use their loading data in an unsupported chamber.

Plated bullets seen to cause problems also, bullet set back on chambering. . https://www.thehighroad.org/index.php?media/albums/kaboom.24/

There were so many Glock Kabooms that i stoped saving photos of them. https://s338.photobucket.com/user/joe1944usa/slideshow/Firearms and Reloading/KABOOM

Human error causes most KABOOMS.


This old guy (me) likes steel frames.

 

[AK103K]

When was the last time anyone reported their Glock blowing up? I thought this had been resolved a good while back. And wasnt it just a .40 issue?

Ive been trying to wear out a 17 for about a decade now, and have managed to break a couple of springs and a rail, and Glock even replaced the frame and rebuilt the gun for free, this past spring, 9 years out of warranty. The only thing left still original, are the barrel and slide, and they have over 150K on them. Havent blown up yet. But Im still trying.

 

[ATLDave]

Same thing as kabooms in any other gun? Too much pressure for the case to contain.

As others have noted, there were certain Glock models in certain generations that left a lot of brass exposed. I don't think that's been the case for current production Glocks for quite a while. But if you combine the older, minimal-support Glock chambers with .40 reloads made with sensitive/spiky powders (such as the popular Titegroup), it doesn't take much to blow out the case. Serious setback, or a case that has been bulged a couple of times before, or a double charge... any of those would do it. And the lack of case support didn't give much safety margin to "bail out" the reloader who made such a mistake.

I don't really think this is a matter of particular concern these days.

 

[ATLDave]

When was the last time anyone reported their Glock blowing up? I thought this had been resolved a good while back. And wasnt it just a .40 issue?

Their early-design 10mm barrels also left a fair amount of brass exposed. Loading .40 with Titegroup, or loading 10mm to max loads, and then putting that in a capacious chamber with a feed ramp cut deeply into it is a no-margin situation. One mistake by a loader was going to be punished a very high percentage of the time.

But, yeah, I think they resolved that particular weakness a good while ago.

 

[243winxb]

Generation 3

later in the Generation 3 all would be switched to the same frame with the extra pin for the locking block. Additionally the frames themselves were strengthened. This came around the development of the .357 cartridge. This caliber required a stronger frame than the Generation 2 so this was built into the Generation 3.

http://www.sadefensejournal.com/wp/the-4th-generation-glock-new-standards-for-perfection/2/

Seems a stronger frame & extra pin was an improvement?

 

[<*(((><]

My brothers Gen3or4 10mm has an unsupported chamber similar to what the early 40s had. He was getting Glock smilies on the brass coming out. It’s best to do the plunk test and see how much the feed ramps eat into the chamber support on guns, especially Glocks. Most Glocks nowadays are fully supported, which is why I was a little surprised in looking at my brothers brass from his Gen3or4 10mm. I told him I would be buying a Lone Wolf barrel that is fully supported and shelve that Glock barrel instead of fighting having to “bulge bust” the brass and weaken it prematurely.

One thing that is always in my mind is that Glock was originally designed for the 9mm. Whereas Smith’s M&P line was originally designed around the 40. I believe this had some bearing on the early generous chambers of Glock with the 40, wanting to ensure reliability at the expense of brass life.

 

[<*(((><]

But more to the OP point it is my belief a lot of the kabooms early on in semi auto guns were from ammo being in in unchambered and chambered each day causing bullet setback creating an over pressure scenario, combine that with the early unsupported chamber design and one had the perfect storm.

Now there are good self defense ammo designs that have a crimp below at the base of the bullet to provide a shelf to prevent bullet setback which is nice. Or people should get in the habit of leaving the gun chambered and securing it in a rapid access safe or only unchamber and recharger so many times before using the ammo up at the range and buying new replacement SD ammo.

here’s a good link about bullet setback and reloading techniques. I haven’t read the whole article but it details the problem and how to test crimps for sufficient resistance. It also towards the bottom shows some nickel cases ammo with the setback crimp I was mentioning.

http://www.massreloading.com/setback.html

 

[JohnKSa]

Glock Kabooms (kB!s) were most associated with .40S&W ammunition and reloads and there probably wasn't a single explanation that covered all the bases.

The most credible explanations I've seen related to a batch of too-soft .40S&W brass from a major manufacturer and a sensitivity to setback in the 180gr .40S&W loading that could double discharge pressure.

There is also potentially some issues with shooting lead bullets in the polygonal rifling although this is not a consistent problem. Some Glock barrels seem to tolerate lead well, others that are apparently identical won't and even modest amounts of lead ammunition can cause significantly increased discharge pressures which can become catastrophic on their own with enough shooting, or that can be "boosted" if a jacketed round is put down an already lead-fouled bore.

There's been a lot made of chamber support issues in the Glocks, but unless there's some other problem, the level of chamber support, even in in the early .40S&W Glocks, is sufficient for safe operation with any decent quality factory ammunition. As noted, it could cause early weakening of the cases for reloaders and that issue may have also contributed.

The Glock design also allows the gun to fire slightly out of battery. The barrel will still be locked to the slide--there's an interlock that prevents it from firing unlocked, but potentially it might fire enough out of battery to cause early unlocking and the potential for a blown case.

Seems a stronger frame & extra pin was an improvement?

This change was related primarily to durability issues (mainly with locking blocks, as I recall) in the non-9mm calibers. It wasn't supposed to increase the gun's ability to handle pressure as that is controlled by the interface of the barrel and slide which hasn't been changed at all as far as I can tell.

 

[fxvr5]

I think it's important to make a distinction by what is meant by kaboom.

1. A case rupture. Generally a case blowout caused by too much of the case exposed (bad case support by the chamber) perhaps combined with high pressure, weak brass, etc. But a weak case can cause it by itself.

2. A split barrel as shown in post #6. Bad barrel or seriously overcharged round destroying a good barrel.

 

[fxvr5]

The Glock design also allows the gun to fire slightly out of battery. The barrel will still be locked to the slide--there's an interlock that prevents it from firing unlocked, but potentially it might fire enough out of battery to cause early unlocking and the potential for a blown case.This change was related primarily to durability issues (mainly with locking blocks, as I recall) in the non-9mm calibers. It wasn't supposed to increase the gun's ability to handle pressure as that is controlled by the interface of the barrel and slide which hasn't been changed at all as far as I can tell.

The Glock slide can't be very far out of battery and still fire because the primer will be moved far enough off-center that a firing pin hit won't ignite the primer. See this link for an example: https://www.ssusa.org/articles/2018/8/14/firing-out-of-battery/

 

[crestoncowboy]

A split barrel as shown in post #6.

Yeah, that's what I was saying. I've had 2 cases rupture in 10mm with factory ammo. But both were in 2 seperate colts and nothing was really hurt (other than blowing my delta emblem off of my grip.) I also used that ammo almost entirely in an early 3rd gen G20 and a G29 and never had one fail. They werent fit to be reloaded but didnt fail.

 

[JohnKSa]

The Glock slide can't be very far out of battery and still fire because the primer will be moved far enough off-center that a firing pin hit won't ignite the primer.

Correct.

Here's an excerpt from a document I put together for my own use based on measurements I did myself on a number of Glocks. The movement of the primer relative to the firing pin as the barrel unlocks is addressed. In a cartridge with a small primer, it's a positive safety, in a large primer, maybe not so much.

It's something I wrote mostly for myself, so it's not really light reading. This was all done on Gen4 or older Glocks. I don't expect that the Gen5 guns will be significantly different, but the much smaller single-stack Glocks may be different and I'm not claiming that the information applies to them.

There are two ranges of slide positions where the trigger will operate and release the striker. However, only one of these stages will reliably cause the pistol to fire.

The first range isn’t really a range at all—it is when the slide is fully forward and the gun is in full lockup. Obviously this is where the gun is designed to operate and it is completely safe to fire the gun with the slide fully forward.

The second stage is with the slide anywhere between fully forward and about 3mm back from the fully forward position. In this stage, the barrel locking surfaces are still maintaining at least 40% engagement with the slide locking surfaces. Under normal circumstances it should not be dangerous for the gun to fire in this position in fact it’s unlikely that there would be any measurable difference in firing in this slide position versus moving the slide forward to the fully forward position. To get a feel for the range of motion possible in this stage, test an unloaded Glock by operating the slide fully, then pulling the trigger back through the first stage. At 2.4 to 3.0mm of rearward slide travel, the connector is deactivated by the ramp/cam inside the slide and about the same time the striker/firing pin safety moves far enough upward to block the firing pin. It’s sort of a roll of the dice as to which starts working first to disable the firing mechanism, the striker safety or the connector. It will vary from pistol to pistol, primarily based on wear to the connector and the ramp/cam.

The next stage of slide motion (past about 3mm of rearward travel) disables the connector via the ramp/cam machined inside the slide—in this stage the end of the trigger can not contact the connector and therefore can't drop the striker.

First, due to the nature of the locking arrangement between the barrel and slide, the barrel drops in relation to the slide as the slide moves backward. The diameter of a small pistol primer is 4.38mm and a hit at the edges is very unlikely to fire the primer—therefore dropping the rear of the barrel by around 2 mm is sufficient to move the primer of the round down far enough that the striker won’t hit it. On a normal Glock, the locking surface of the barrel is still at least partially engaged with the locking surface on the slide until there is approximately 2.5 mm of downward deflection at the rear of the barrel. A large pistol primer has a diameter of 5.48mm. Clearly, if this was our only safety blanket, the possibility of a true out of battery event is a possibility here, but fortunately, it’s not.

Second, the total compression distance of the striker spring is about 10.2mm. That means for every millimeter (less than a 25th of an inch) that the slide moves backward, the striker spring compression distance is reduced by about 10%. After just 3mm (less than 0.12") of backward movement by the slide, the striker compression is down by 29%. The energy stored in a spring is related to the square of the compression distance of the spring. Therefore, a 3mm reduction in compression distance (30% reduction in striker spring compression distance) would reduce the energy stored in the striker spring by 50%--half. Clearly, moving the slide back even a relatively small distance reduces the striker energy considerably.

The half dozen or so Glocks measured unlock (barrel and slide locking surfaces lose contact) between 4.1mm and 5.3mm of rearward slide travel. The amount of rearward slide travel equates to the amount of striker spring decompression since moving the slide back decompresses the striker. The spring energy formula tells us that the amount of energy stored in the striker spring has been reduced by about 64% at 4.1mm of decompression and reduced by 77% at 5.3mm of decompression. The energy drop is significant (2/3 to 3/4)--probably sufficient to prevent the gun from firing.

Examination of a case that was intentionally fired with the slide as far back as it could possibly be moved without disabling the trigger mechanism. The case was primed but had no powder or bullet for safety reasons. There was a very light and off-center primer strike. The light primer strike indicates that either the firing pin safety partially retarded the forward motion of the striker or the reduced compression of the striker spring lightened the strike. In fact, the design of the Glock insures that both occur as the slide moves backwards.

The primer strike was no more than 1mm off center. Assuming that the primer strike on this pistol is normally centered, this would mean that the barrel was deflected down by about 1mm at the time that the striker fell.

Based on measurements of a half dozen or so Glocks, the locking surfaces of the slide and barrel were still well engaged (45% or greater) at the maximum amount of downward barrel deflection at which the trigger could drop the striker. The fact that the slide & barrel surfaces are still engaged also means that the cartridge is still contained within the locked breech & chamber.

The fact that the striker has fallen does NOT necessarily mean that the gun will fire. In half the guns, the striker safety prevented normal motion of the firing pin before the ramp/cam disconnected the trigger bar from the connector. There appears to be a correlation to the number of rounds fired and the winner of the race to see whether the firing pin safety or the connector will disable the gun first. In the guns with more rounds downrange, the firing pin safety tends to win. This probably indicates wear on the "ear/hook" of the connector, the part of the connector that engages the ramp surface inside the slide; one reason to keep that surface lubricated with a light grease.

Even in the cases where the firing pin safety didn’t prevent the striker from moving normally, the energy stored in the firing pin spring was reduced by an average of 47%.

As previously mentioned, the barrel must deflect downward about 2.5mm before the barrel hood loses contact with the slide. The fired case test indicated that the barrel had deflected downward only about 1mm and therefore the barrel was still engaged with the slide. The measurements showed that none of the tested pistols would fire (trigger was disabled) if the downward barrel deflection approached 1.5mm.

The testing shows that the striker will not drop after the barrel and slide unlock, and that the safeties on the pistol will deactivate the firing mechanism well before the pistol’s locking surfaces completely disengage (i.e. while the cartridge is still contained by the locked breech & chamber).

• Moving the slide backwards by around 3mm disables the firing mechanism by means of the striker safety preventing the firing pin from protruding through the breech or by the deactivation of the connector preventing the trigger from releasing the striker. The locking surfaces are still engaged by 45% (or more) at the point that the firing mechanism is disabled.
• Moving the slide backwards causes the breech to drop. This is a function of the normal operation of the locked breech action and is impossible to circumvent. In a caliber using small pistol primers, the pistol’s locking surfaces will still be engaged by about 50% (and the cartridge still contained) when the primer has dropped too low for the striker to hit it.
• Moving the slide backwards decompresses the striker spring—reducing the force of the firing pin strike. By the time the slide is far back enough that the pistol’s locking surfaces have fully disengaged, the striker spring energy will be reduced by an average of 70% percent.

The bottom line is that while a Glock can discharge with the slide out of what is commonly referred to as "full lockup", the barrel/slide locking surfaces will still be about 50% engaged in the worst case "out of battery" discharge.​

 

[bearcreek]

When was the last time anyone reported their Glock blowing up? I thought this had been resolved a good while back. And wasnt it just a .40 issue?

The gun community has an extremely long but very selective memory. Look at the number of people still spouting the BS about AR's needing to be squeaky clean in order to be reliable.

 

[Logwood]

Never witnessed a "kaboom" of any kind myself. I seem to remember back when Glocks first came out, there was some concern about shooting unjacketed lead bullets through the guns.

 

[Caplock]

Just started reloading for my Glock 40.
Loaded up 100 rounds on a single stage press. Every round reloaded exactly the same way. I'd say about 5 % of the loaded rounds failed a set back test of pushing the loaded round into my reloading desk. Never had this happen with 9mm or 45 acp. Took the failed rounds apart. Resized the cases for a second time. Reloaded and now the bullets won't move.
Spring back after the case was sized the first time?? I dont know but I bet if one of those rounds had been chambered and shot the pressure would have spiked and maybe kaboom.
I will forever check every 40 reload for bullet set back period.

 

[barnetmill]

But more to the OP point it is my belief a lot of the kabooms early on in semi auto guns were from ammo being in in unchambered and chambered each day causing bullet setback creating an over pressure scenario, combine that with the early unsupported chamber design and one had the perfect storm.

Now there are good self defense ammo designs that have a crimp below at the base of the bullet to provide a shelf to prevent bullet setback which is nice. Or people should get in the habit of leaving the gun chambered and securing it in a rapid access safe or only unchamber and recharger so many times before using the ammo up at the range and buying new replacement SD ammo.

here’s a good link about bullet setback and reloading techniques. I haven’t read the whole article but it details the problem and how to test crimps for sufficient resistance. It also towards the bottom shows some nickel cases ammo with the setback crimp I was mentioning.

http://www.massreloading.com/setback.html

The guns I use for self defense are seldom unloaded and when done it is more for cleaning and other maintenance. Setback is a real issue especially since I often use +P+.

 

[jmohme]

I think Glock Kabooms are a lot like Ford Pintos exploding.
Both have been known to happen, but I have never seen either one first hand.

 

[Rule3]

Hm, AFAIK most blowed up Glocks were early .40s which had an insufficiently supported feed ramp. This, coupled with cheap brass, resulted in some ruptured cases and kabooms.

View attachment 877930

And so endeth the story

 

[Pat Riot]

I have never witnessed a Glock “Kaboom”. I do not know anyone that has ever mentioned one. I do recall reading something about the .40 S&W issues many years ago but I do not even recall the details on those articles. Honestly, I wasn’t interested in Glocks when the first .40 S&W guns were released so I skimmed through anything “Glock” and moved on.

I did not own a Glock until 2005 when I bought a Gen 3 G34. That is when I started paying attention to “Glocks”.


Edit: I wish auto correct would have some “Kabooms” sometimes. Then maybe someone would fix those issues...Grrrr

 

[ATLDave]

I have seen a Glock kaboom... but it was a 9mm major USPSA race gun built up from a G17. Case blew out at the feedramp... but I wouldn't blame anything about that on Glock.

The guy who owned that gun took it over to Glock USA in Smyrna and they gave him a new frame! I'm not a Glock fan, don't own a Glock, would sell a Glock if someone gave me one... but it was impressive customer service from them!