The gun is all used up

I went to a USPSA match today and my gun barrel fractured and locked up my gun. This is a cropped version of the picture I tweeted about shortly after the incident:

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Robb Allen almost immediately asked the obvious question, “Your own loads or factory?” And of course the answer was they were rounds I had loaded myself. In many situations this would be the end of the story. The shooter had a squib (a round with no or insufficient powder) which resulted in a bullet stuck in the barrel and the next round set off the automatic self-destruct sequence of events. Another way it could have happened was a round got double charged or the wrong powder was used. In any case it is relatively easy and frequent that handloaders blow up their guns through their own carelessness.

But as Ry pointed out the head of the shell casing is still there which probably means there wasn’t an over pressure event involved. I was able to hammer the gun open far enough for the shell casing to drop out and confirmed Ry’s suspicion:

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This is a perfectly normal looking piece of brass. Even the primer looks normal so there was no overpressure event involved. I tried putting it in the case gauge and it would only go in about halfway. The chamber of barrel is now, of course, large than spec and the brass expanded just a bit more than normal even though it can’t be seen with the naked eye.

I tried for quite a bit to get the gun open in the hopes that I could remove the barrel but I wasn’t able to get it open any beyond this:

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You can’t see it in the photograph but the feed ramp also split.

I finally just closed it up:

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I don’t know what the root cause was. I wonder if it wasn’t a timing issue which caused some abnormal stress because I had a broken link with this barrel once before.

Something that is interesting to me is that I had the lugs break on the original STI barrel after about 20,000 rounds and this barrel failed after almost exactly the same number of rounds. I have known the gun was living on borrowed time for nearly six years now so I can’t really complain a lot.

I’m not going to try to get the gun repaired. As Barb, essentially, and Gay_Cynic said, I used the gun up.

Update: I should have said that the shot sounded and felt almost normal to me. The recoil cycle wasn’t quite right but there wasn’t a greater than normal impulse or BOOM!

29 thoughts on “The gun is all used up

  1. You should drop KKM a line, let them know, show them the pics. They might well want the barrel back for testing and examination. I know if I manufactured something *I’d* want to understand the nature of catastrophic product failures. No idea if you might get a free or discounted replacement barrel out of it.

    • The barrel was purchased in early 2001. I doubt there is much to be learned that relates to their current products.

      • If you are not going to return the barrel to KKM and you have not disposed of it yet, may I ask you to send it to me for a metallurgical evaluation. I am a forensic engineer specializing in metallurgical failure including a number of firearms related incidents. My CV can be downloaded from the website. I would be interested in doing a professional write up. You can receive credit as a co-author.

  2. The fortunes were with you.

    Now wait for a gun buy back and get some money from the grabbers while giving them a paper weight.

    • I also noticed that the split ran through the cross bar of the “4”.

      I wonder if the punch detail had a chisel point or if it was radius-ed. Clearly, the portions of the stamp closest to the base of the bullet had the highest pressures. The pressure drops of very quickly as the bullet moves down the barrel. Peak pressure occurs about where the base of the bullet clears the case mouth for a modern pistol round.

      I was once leafing through an engineering textbook. They had a picture of an airplane propeller. The design had passed all of the testing but was fracturing in the field. The production blades had identifiers stamped in them on the back side (tension) fairly near the hub. A very big no-no.

  3. I don’t have a link to give you but I am certain that a short while back I read an article on the web that many police departments were switching from the 40 S&W back to the 9MM because, in part, the 40 was causing their pistols to shoot themselves apart faster than the 9MM.

    • .40 Does beat on guns, I think the bigger issue is the high volume shooting Joe does with it.

      Given that the case is reloadable, and you didn’t feel the need to describe how that last shot sounded and felt, I suspect it is just the end of the gun’s lifespan. The improperly fitted barrel probably didn’t help….but honestly the numbers you have through that gun, if it died pre-mature, it did so trivially.

      Can’t wait to see what you replace it with.

      • This looks like a fatigue failure to me, not a strength failure. If that’s the case, then the barrel was indeed at the end of its life like you said. Any over stress from the hand-loads may have sped up the crack propagation, but it’s hard to complain after 14 years of reliable service (assuming it was reliable).

        • All my handloads have been lower powered than factory. I deliberate load for minimum recoil while making “Major Power Factor” for USPSA matches. 180 grain factory ammo typically runs about 1025 fps in my gun. My handloads are typically about 950.

  4. Bike guys have a saying along the lines of all stuff breaks and wears out. It’s kinda nice to see that sign whenever I walk in to my local mechanic with Yet Another Broken Component™. My mechanic always says the same thing when he’s placing an order for new parts: “It’s my opinion that anything you use and enjoy until it’s completely worn out was money well spent.”

    I’d agree with that. Looking forward to… erm… new gun day I guess? (and of course, post photos!)

  5. The sign at a local motor sports related repair shop:

    “If it’s not breaking down, you’re not going fast enough!”

    Looking at your .40 reloading stats, you have been going fast enough…

  6. How can you double charge those little bitty cases? I reload my own 9mm. and there is no way it can be double charged, the powder overflows the case if you try. A full charge fills the case 75% leaving just enough space to seat the bullet to the top of the powder.

    • It depends on the powder load. I think it was fairly light loads of Titegroup (4.5 grains) that I could get double charges without having problems seating the bullet.

  7. I had a manager once who kept broken parts from the engine rebuild of his 1968 Alfa Romeo Julietta in his office. When interviewing potential hires, he would casually ask if they knew what the parts were (piston, valves, camshaft). Knowing went a long way to getting a job, which included the unexpected benefit of driving his Alfa out to lunch every once in a while.

    Embedded in lucite, your new paperweight could serve a similar function.

  8. On the chamber gauge: I wonder if that test really indicates an oversize chamber. The min chamber dimension is a hair larger than the largest case dimension, of course. So a case gauge would be sized for a sliding fit for the largest spec case dimension. That would correspond about to the min chamber size. If your chamber is near max, then firing a round would expand the case to fit that dimension, then when the pressure fades it would come back just a bit — but would it come back far enough to fit in a case gauge?
    I suppose one could test empties from a known good barrel to see.

  9. joe:

    the .45 acp operates at about 21,000 lbs pressure. i think the .40 s&w maximum is about 33 to 35,000 lbs pressure.

    the chamber dimension, outside diameter, for a .40 s&w is gonna be the same as for a .45 acp ….. the chamber, then, in a .40 s&w is subject to more pressure than the gun & barrel were designed for, even w/ “moderate” loading.

    fatigue failure, from constant exposure to pressures and battering more than the gun & barrel & chamber were originally designed for, and which govern the saami specs even to this day. load your .40 to around 21,000 lbs and i doubt this would happen.

    given the choice between john m. browning’s judgment and those of present day designers, and i will take & heed mr. browning opinion (and advice) every day. simple as that.

    john jay

  10. p.s.
    correction–
    “…. mr. browning’s opinion (and advice) every day.”

    p.s.s. and, yes, i would heed mr. browning’s judgment on what constitutes a mild load in the stead of yours. no offense meant. but, you are probably juicing the gun. and, its components.

    you might “consult” quick load as to the pressure you are generating to get your 950 fps velocities. probably greater than .45 acp or .45 acp +, would be my guess. i don’t know for sure, …. , but, something expanded the chamber and caused the ultimate failure, that’s for sure.

  11. Pingback: SayUncle » Guns break

  12. One possible thing is a microfracture. All materials are subject to fatigue as well as static stresses. When a loading is applied, released, applied again, over and over, this causes fatigue in the metal. This is exacerbated if there are small, even microscale defects in the material. It is possible that, as stampings were made or machining was done, a small fracture occurred, or that the base steel blank was not properly stress-relieved. Thousands of cycles then lead to eventual failure at this defect.

    Another interesting thing to note is the way it failed. Most metals, being ductile, expand before they fracture. This barrel appears to have split with little to no deformation prior to the split. This kind of brittle behavior in a ductile material is characteristic of fatigue failure rather than static (i.e. overpressure) failure. Consider that, with most overpressure rounds, the barrel will bulge before it splits. It didn’t in this case.

  13. As a guy who runs an engineering firm, I am always amazed how gunnies tend to obsess over mechanical failures in what are essentially little stumps of common metal that are loosely attached to one another.

    Everything wears out, and everything breaks. It is exceptionally rare that a human can see the limits of a part before it fails. From a mechanical perspective, firearms (even well used ones) live a pretty gentle existence – but that can only forestall the end, not avoid it.

    I’d do what the others here suggest: thank the engineers who designed a product that prevented a catastrophic failure from hurting you; save the remnant for the next gun buy-back in a overly-budgeted town near you; and (most importantly) – buy something fun for yourself and shoot the hell out of it.

    Wash, rinse, repeat.

    • Quick note: I forgot to mention that I think your post tag is perfect: “The Gun Is All Used Up”

  14. Well, if you can get the top end off without damaging the frame any more than it already is (*if* it is – ramped barrel, right?), then you have a perfectly fine base to throw a .22 conversion kit on for a dedicated pewpew – get one with a threaded barrel and throw a can on for even quieter fun!

    (My own experience is with a Springfield frame that was bubba’d for racegunning – dude was selling a .38 Super top end at the same time – along with an Advantage Arms kit and a baggie of “evidence gun take-off” innards. Previous owner had the frame ramp milled out for a ramped barrel, but the AdArms kit doesn’t care.)

  15. Really interesting. I’ve never seen anything like that before. Hopefully you will keep this post up so others can see what can and does happen. Too many people only follow minimal safety procedures. Also would like to see the test results from the metallurgical engineer that offered to do it. Hope you take him up on it.

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