10mm v. 40 S&W v. 357 SIG

atblis said:

Thanks for the offer. Which caliber do you have?

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For the G20:
Factory 10mm
Lone Wolf 10mm
Lone Wolf 357 Sig

For the G29:
Factory 10mm
Storm Lake 10mm
All standard length for stated firearm.

stick figure pic is awesome!

atblis said:

Thanks for the offer. Which caliber do you have?

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I have a glock 33 357 sig barrel you can use.

Supported vs unsupported chambers

I appreciate the caliber comparison information. I am not trying to turn this into a Dodge, Ford, or Chevy discussion but I would like to know if all manufacturers have the supported vs unsupported chamber issues or is this only a concern for Glock pistols?

I have a Sig 226 and 239 both in .40. I have been thinking about getting barrels for .357 Sig. I would appreciate comments from anyone with firsthand experience.

I have not started to reload yet so I have not examined the cases for excessive bulging near the case head. Is this the easiest way to tell if my chamber is unsupported?

Thank you

Minuteman said:

Your first image still not loading.


Found this, doesn't look like it holds water, or over generalization:

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I understand everything but the 40 S&W. Having a Glock 23Gen4 with over 500 rounds through it, I've not experienced any sort of odd misfires. Is there some sort of reliability issue people are pinning on 40s? If so, I haven't seen it.


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I dunno, the few .40's I've shot worked ok too. I just thought this stick figure drawing was kinda funny. I'm suspecting in the mind of the person drawing it, there's some reliability issues, at least more so than the other calibers.

Hopefully someone will chime in with some data/opinion.

Minuteman said:

I dunno, the few .40's I've shot worked ok too. I just thought this stick figure drawing was kinda funny. I'm suspecting in the mind of the person drawing it, there's some reliability issues, at least more so than the other calibers.

Hopefully someone will chime in with some data/opinion.

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Kinda funny? I got a really good belly laugh out of that drawing....still laughing. The guy is even giving the finger in the .45 drawing, missed that the first time.

Minuteman said:

I dunno, the few .40's I've shot worked ok too. I just thought this stick figure drawing was kinda funny. I'm suspecting in the mind of the person drawing it, there's some reliability issues, at least more so than the other calibers.

Hopefully someone will chime in with some data/opinion.

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The drawing depicts that glock 40cal pistols like to kaboom more than other guns. Some think it was due to lesser supported chambers. I have no opinion. My glock 27 has a ton of rounds through it and it works just fine. I've put many thousands of rounds through other 40 caliber pistols without a problem. I think if there was a problem it was in the past.

The reason(s) have never been conclusive diagnosed, but there have been rashes of well documented KaBooms of .40 Glocks.

Not frequently enough for me to obsess ( if I otherwise cared for .40 ) , but definitely significantly larger than zero.

Most Glock kabooms AFAIK have involved reloaded ammo.

Factory ammo might get the famous Glock smilie but I have never experienced a problem. I have a G29SF and a G20SF.

I shoot Underwood full power loads in 10mm. Not 40 but the 40's parent cartridge.BTW.

ETA-The Glock warranty is voided if you shoot reloaded ammo. POI.

And MM's stick figures in addition to bringing a grin, are an excellent summary of the viewpoints of 10-15yrs of ongoing debates .

Of course the omitted wild card is .357 Sig ( or .357 mag for us dinosaurs ). Or MM is actually three steps ahead of me, and deliberately left them out as commentary on their moderate peak usage, and he is predicting further declines in popularity. ( I'm predicting holding at least current level, possible small gains, but that's why there's horse races.)

1time said:

The drawing depicts that glock 40cal pistols like to kaboom more than other guns. Some think it was due to lesser supported chambers. I have no opinion. My glock 27 has a ton of rounds through it and it works just fine. I've put many thousands of rounds through other 40 caliber pistols without a problem. I think if there was a problem it was in the past.

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The use of lead bullets in factory barrels (don't do this) and unsupported chambers in the early Glock .40 S&W guns contributed to the kaboom story. These issues have been addressed through a barrel redesign for the chamber support issue and a warning not to fire lead bullets through Glock factory barrels. Reloads also have played a role in some instances but the technical talk on that subject is over my head as I don't reload so I found some discussion elsewhere to better understand it.

Other factors are discussed in the post information below from another forum. This information was found at:

http://www.downrange.tv/forum/index.php?topic=1698.0

#1--------------------------------------------------------------------------------
Glock Kabooms...Myth or Not? - MarkCO

I have read the reports where folks say they have 500, or even 5,000 rounds through their Glock with no problems. That is nice, but by no means is it significant scientifically.
I bought the first Glock .40 the local gunshop sold and started shooting IPSC with it. That first G22 went about 23K rounds before it failed. The reason it failed, and documented by myself through exhaustive metallurgical testing, and concurred with by Glock, was due to overpressure caused by lead bullets. Funny thing is that, as I write this, sitting right here at my desk, is a page full of numbers, numbers that luckily I recorded prior to the failure. I was shooting over a Chronograph when the gun blew and had over 120 rounds individually recorded. Each round had been measured and each powder charge individually weighed. I know EXACTLY what the loads, powder charges and velocities were. I look at the numbers now and wonder how I did not pick up what was occurring. But hey, I was young. This was almost 10 years ago.

As I write this, I have a G22 with over 80,000 rounds through it, a G35 with over 15,000 rounds through it, a G27 with over 20,000 rounds through it and I sold a G24 with 15,000 rounds on it, a G23 with 6,000 rounds and a G35 with 2,000 rounds on it (does not count since a KKM barrel) So I have fired 159,000 rounds of .40 through Glock factory barrels.

I have pressure tested lead bullets fired in actual Glock barrels with controlled test conditions and the same loads fired in conventionally rifled barrels. Then I fired jacketed and copper plated bullets in the same conditions to test for pressure increases there. Conclusion is that lead bullets, yes, even the 24 BHN variety, increase pressure after only a few rounds fired. When the pressure reaches an unsafe level has to do with the powders pressure curve, temperature, bullet hardness, bullet grain structure. Weak cases do let go, but do not result in the same type of damage.

When a Glock is overpressured, the shooter is rarely injured beyond a few cuts or bruises on the shooitng hand, none that I have seen have been permanent. And how many have I seen? To date I have personally inspected over 40 blown Glocks that were the result of overpressure. I have reviewed documentation on over 120 others. And, yes ALL calibers were represented.

And how would I know what I am doing, besides just being a shooter? I am a forensic engineer (mechanical) who investigates accidents and failures for a living. I have been qualified in court, as an expert (which is not easy these days). And for the record, the firm I work for does more defense work than plaintiff work. We work for who hires us and, sometimes, our clients do not like our findings, but that is the breaks, facts are facts, evidence is evidence.

Glocks are not perfect, nothing man-made is, but I trust my life to their reliability. I reload (couldn't afford to shoot if I did not). For me, I choose to shoot plated bullets which cost me a few dollars a thousand more than lead. I save on the cleaning stuff and the cost is about the same as lead. I also use the factory barrels, exclusively now (I sold my KKM barreled G35).

The overwhelming majority of blown Glocks are from lead or poor quality reloads. A few are from bad factory loads and a few from defective aftermarket parts. I must beleive that there are a scant few that have had manufacturing defects, but I have not seen one yet that casued a KB. If I do, Glock will surely be hearing from me, and I believe they will do the right thing.

Hope this helped.

#2--------------------------------------------------------------------------------
Glock kaBOOMs - MakeMineA10mm
The original Glock is the 17, and it was designed around the 9mm cartridge package. It is completely and totally engineered to be absolutely safe with that round, and the 9mm seems to be the Glock with the least kaBOOMs, even though it has, by far, the largest number of pistols made for it's caliber (world-wide -> in the US, the 40 is catching the 9mm, maybe even surpassing it). Why is this so?

Well there are many reasons. Ammunition problems are a primary concern, however there is also firing out-of-battery, lead bullets, unsupported chambers, and other factors. To break it down, we have to look at how the Browning locking design works, and this takes quite a bit of explaining.

First, assuming a properly chambered and functioning cartridge, the following occurs:

1. The firing pin hits the primer and the primer/powder ignites.

2. The rapidly expanding gas propels the bullet into the barrel and simultaneously swells the brass case into the chamber walls obturating the breach.

3. The barrel and slide begin moving rearward, in a locked-together position for approximately 3/32 of an inch.

4. How soon and quickly the slide/barrel unit begins moving is determined by the force of the round being fired compared to the inertia of the slide/barrel unit. The heavier the slide/barrel and/or the lighter the force of the round being fired, the slower the slide/barrel open and move.

5. As the slide moves rearward, it is compressing the recoil spring.

6. Just after the bullet leaves the barrel and pressures rapidly drop in the chamber and barrel, the cam on the barrel begins it's thing. This causes the barrel to drop downward, out of it's locked position.

7. The slide continues rearward, without the barrel, and the extractor is hanging onto a segment of the case rim, thereby extracting the now-spent case.

8. The slide, near it's end of rearward movement, draws the empty case into the ejector and the case is pivoted out of the grasp of the extractor and out the ejection port.

9. The slide stops.

10. The recoil spring returns the slide to battery, with the slide's pick-up rail stripping a fresh cartridge out of the magazine and feeding it into the chamber in the process. (The feeding of the cartridge is another process altogether, and doesn't have to do with kaBOOMs, so I'll not refer to it further.)

This leads us to question several things, in a certain order about kaBOOMS:

1. Look at ammunition first, because there's a lot less going on with it. It's either defective in excessive pressure, or weak brass, and that's about it. Two things to check makes it much easier to point at/eliminate first.

2. Look at the bore of the pistol. I have in my possession a Beretta 92 barrel that swelled up when a round was fired immediately after a squib load left another bullet in the bore, obstructing it. It is also relatively easy (in some cases) to see if the bore was obstructed in some way, which lead to the kaBOOM.

3. As a last resort, we have to look at the mechanics of the firearm. This is last, because it is complicated, with many things happening simultaneously, and therefore not an easy yes/no test.

By becoming familiar with the above description of the Browning system and looking at the barrels and slides, you can figure out for yourself, that the metric Glocks (9mm and 10mm) are stronger and safer Glocks from a couple points of view:

1. Barrel walls are thicker on 9mms than 40S&Ws. They have the same outside diameter, but the 40 has a 1mm bigger hole bored through it. Likewise the 10mm and 45 have the same O.D., but the 45 has over a 1mm bigger hole bored through it. Thicker walls means safer.

This is especially true with the 9mm/40S&W comparison. The 9mm, 10mm, and 40S&W all work in the same pressure area: ~35,000 p.s.i. The 40 has a MUCH thinner barrel to contain the same high pressures that the 9mm does with its much thicker barrel. This is not such a big factor with the 10/45 comparison, because the 45 can compensate a great deal for that thinner barrel by operating at lower pressures (~21,000 p.s.i. for +P loads). (This is counter-acted when people convert 45s to wildcats such as the 45Super/40Super/400Cor-Bon, taking away the advantage the 45ACP enjoys here.)

2. Slide mass. Slide/barrel mass (a.k.a. weight) is what gives the slide/barrel unit the inertia to keep from opening too early. The thicker barrels for the metric caliber Glocks, already referred to above, contribute some of the additional weight, but mainly it comes from the weight of the slide.

In the 40/9mm I have not compared slide mass, so I will not comment, other than to only say that, on my 9mm Glocks, I can see that the slide walls are full-thickness for only about 1-1/2 inches forward from the breachface, and I must assume that 40 Glocks have full-thickness slide walls all the way to the muzzle. Still, this will barely compensate for the difference in barrel weight, which means, IMO, slide velocity is excessive in 40S&W Glocks. (This is a major part of the reason MarkCO recommends stronger springs, in differing increments, for all Glocks other than 9mms.)

Likewise, in the 10mm, the slide walls are full-thickness all the way to the muzzle, whereas, in my G-21, the slide walls are thinned very close to the breach. If a G-21 had full-thickness slide walls all the way to the muzzle, it wouldn't function reliably as the slide/barrel unit's inertia would be too high.

This is because the engineers have to pick a slide/barrel unit weight that is as close to the ideal for the middle of the road power-level cartridge as is possible, while still giving full safety for the anticipated (SAAMI max) most powerful ammo to be fired in that caliber weapon. (This is why I am very concerned over conversions of the G-21 to 40 Super/45 Super/400 Cor-Bon, because all of these cartridges operate at higher chamber pressures AND higher slide velocities than the highest level the 45+P operates at.)

These inertia/barrel thickness factors only increase your margin of safety. They do not mean that any Glock/firearm are infallible. Any firearm can be made to fail.

The one factor we have not looked at, yet, is the "unsupported chamber".

This, too, is another cause of many kaBOOMs, and it, again, is connected, at least partially, to caliber. For example, if you looked at an engineer's drawing of the 40S&W case, you would see that the web (the area of the sidewall of the case that begins tapering thicker as you get towards the base of the case) starts much farther down the case than the 10mm, which it was designed from. The reason for this was that when 10mm cases were trimmed down to make the first, wildcat 40S&W cases and bullets of 180gr or heavier were seated in them, the case bulged because the heel of the bullet ran into the beginning of the web of the cut-off 10mm brass. Reamers had to be used to shorten the converted cases' web to allow seating the 180gr bullets desired.

When setting up to make 40S&W brass this was a known problem, and to correct it, the web simply starts lower and thickens more rapidly so that it is still the same thickness as the 10mm by the time you reach the base of the case. This is fine, except on chambers which have relatively long tapers to their feed ramps, such as the Glock. What happens now is that a thinner area of the case is over the beginning area of the feed ramp (the "unsupported" area) and with a case that has too brittle brass, or soft brass, or cracked brass, or an over-pressure load, you can have a kaBOOM.

This is complicated by the factor I cited above: Slide Velocity. The higher the slide velocity, the sooner the slide/barrel unit begin moving rearward, and the higher the residual chamber pressures are while this happens. If residual chamber pressures are too high (from say an over-pressure round), and the case is beginning extraction from the chamber, this only aggravates the unsupported chamber problem.

All of this was likewise aggravated, because several companies rushed production of their 40S&W firearms and/or ammunition. Glocks in 40 cal. were out almost simultaneously to the S&W product! Additionally, there are several lots of Federal 40 ammo that are under recall, because they were loaded to the maximum level and proved to not interact well with guns produced hastily (the first 40 cal Glocks). This is why there was such a rash of 40 caliber kaBOOMs when they first came out. Rushed ammo and guns operating at the edge of the safety margin. It was bound to happen.

So basically, what this all means is, that, barring barrel obstruction, and defective ammunition, the safest Glocks are the ones with the best safety margins (thickest barrels and best inertia to power-level of their cartridges, AKA Low Slide Velocity).

To rank them in this quality of greatest safety margin, I would do so thusly:

1. 9mm
2. 10mm
3. 45ACP
4. 357SIG
5. 40S&W
(and then conversion calibers which operate at higher chamber pressures without compensating for slide/barrel inertia
6. 400Cor-Bon
7. 40 Super
8. 45 Super

If one plots out the number of kaBOOMS compared to the number of pistols produced in each caliber, I would be willing to bet that that list would be in the reverse order of my list, meaning the 40S&W has the highest percentage of kaBOOMS and then down to the lowest percentage being 9mm.

Sorry this is so long, but attempting to explain complex concepts takes some room. :-) [MakeMineA10mm]

Here are some links to additional kB! info:
Calibers Glock kB! FAQ http://greent.com/40Page/general/faq-kb.htm
Calibers .40 S&W kB! Report http://greent.com/40Page/general/kb.htm
kB! Pics http://glock.missouri.edu/glock/gkbpix.shtml

Good god dude. If that's an article, post a link to it and not the entire thing.

1time said:

The drawing depicts that glock 40cal pistols like to kaboom more than other guns. Some think it was due to lesser supported chambers. I have no opinion. My glock 27 has a ton of rounds through it and it works just fine. I've put many thousands of rounds through other 40 caliber pistols without a problem. I think if there was a problem it was in the past.

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Ok here's my delema, I'm trying to figure out where you see that this says its about Glock anywhere. It's a cartoon drawing, and a funny one at that.

StickShaker said:

Kinda funny? I got a really good belly laugh out of that drawing....still laughing. The guy is even giving the finger in the .45 drawing, missed that the first time.

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I missed that too first look. It's funnier now the more I think about it.

swinokur said:

Most Glock kabooms AFAIK have involved reloaded ammo.

Factory ammo might get the famous Glock smilie but I have never experienced a problem. I have a G29SF and a G20SF.

I shoot Underwood full power loads in 10mm. Not 40 but the 40's parent cartridge.BTW.

ETA-The Glock warranty is voided if you shoot reloaded ammo. POI.

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"Famous Glock smile"? First heard for me. Meaning: FTE?

Biggfoot44 said:

And MM's stick figures in addition to bringing a grin, are an excellent summary of the viewpoints of 10-15yrs of ongoing debates .

Of course the omitted wild card is .357 Sig ( or .357 mag for us dinosaurs ). Or MM is actually three steps ahead of me, and deliberately left them out as commentary on their moderate peak usage, and he is predicting further declines in popularity. ( I'm predicting holding at least current level, possible small gains, but that's why there's horse races.)

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*swallows*... you give me too much credit, but thx! I've heard that 'most' police agencies are re-looking (and some already moving) back to 9mm. The USSS is/was one of the biggest proponents for 357sig, but they have been also using 5.7 for a few years now; and wouldn't surprise me if they too don't re-adopt the 9mm.

Great info Boundlessdyad, now, in addition to the excellent FBI ammo study report, we now also understand 9mm is 'safer' and safer = reliability. Reliability is the most important quality in a defensive firearm.

atblis said:

Good god dude. If that's an article, post a link to it and not the entire thing.

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It's not an article. It is a single post on another gun forum. Not easy to link to hence the copy and paste.

Minuteman said:

"Famous Glock smile"? First heard for me. Meaning:

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Unsupported chamber and pressure issue.

Buff7mm said:

Unsupported chamber and pressure issue.

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Wow. Thx.

I'd call that a 'frown' because it's downward (standing on base), and because 'it's bad', makes you frown too.

Small one cut away view

Even worse