YouTuber Kentucky Ballistics almost dies from 50 cal explosion

[Mk-211]

He said he got a military chamber, meaning that it was a little bigger than a match chamber.

He doesn't say the size and it doesn't mean squat. Unless we know the dimensions especially near the tip of the bullet, a military chamber doesn't mean much. If the round is jammed into the front of the chamber or rifling, the pressure levels are going way up. Then add in the reloaded round of suspicion...

 

[bat]

Hello.

Here is a couple of close-ups from the videos where he used that sort of ammunition, and show the rounds to the camera:



You can see that the crimp is missing on the SLAP case. Usually all surplus cases are crimped, as is the one from the right.

Here is from another video:



You can see a crimp, but also a dirty neck and shoulder, as if the case has already been fired once, and not cleaned before reloading.

These are indication that he fired a composite lot of ammunition. Rounds of unknow and diverse origin. Maybe even reloaded by differents peoples.

 

[Kano383]

Guns do go kaboom, for a variety of reasons.

In this particular case, the bottom line is: no matter what the guy in the video did, no matter the Slappitude of the rounds used, this rifles's design is stupidly dangerous.

Take a plumbing pipe, stick a 12Ga round in it, screw on a cap with a tiny hole in the center, stick a nail in the hole, and hammer the nail. That's what gangbangers cobble together with hardware-grade materials, and hardware-grade engineering standards.

This gun has no provisions to vent excess gases out, and zero in-built redundancy or any type of safety for the shooter: the breech cap is just waiting to hit the shooter at the first opportunity.

To make matters worse, the two receiver lugs abutting the cap, instead of being designed as safety lugs, are turned into missiles after being sheared off by the cap, and add to the lethality of the whole contraption.

Anybody with a basic understanding of engineering and firearm design would shudder when handed one of these glorified pipe bombs, and asked to pull the trigger on anything larger than a .22 Short.

 

[bat]

I think he doesn't do a thing absolutely wrong, but a series of small mistakes and/or safety compromises which ended up in a total failure when the stars unfortunately aligned.

That often how serious accidents happens to peoples otherwise very smart.

 

[Goosey]

To make matters worse, the two receiver lugs abutting the cap, instead of being designed as safety lugs, are turned into missiles after being sheared off by the cap, and add to the lethality of the whole contraption.

Anybody with a basic understanding of engineering and firearm design would shudder when handed one of these glorified pipe bombs, and asked to pull the trigger on anything larger than a .22 Short.

This is the actual designer of it and some of his other very safe and well-thought out designs.

 

[Kano383]

This is the actual designer of it and some of his other very safe and well-thought out designs.

View attachment 995875
View attachment 995876

Didn't think it was that bad...

 

[Mk-211]

That SLAP-T round in the picture above, that darkened area that was pointed out around the neck and shoulders is from the round being annealed.

You see that a lot in 50 BMG factory round that are going to the military. They figure there's no need to clean what won't be reused.

Yes, there's no factory crimp on that SLAP-T round, it does look like there's a slight crimp on it though.

 

[Hartkopf]

If someone told me the round that blew up was reloaded with pistol powder, I wouldn’t argue.

 

[Mars5l]

Mark Serbu posted a video. He stated it was his making and design but the other guys idea for this design. He's waiting for Scott to send the rifle and ammo to him so they can examine it

 

[daniel craig]

F*** says I.

takeaways:

Wear good Eye pro (imagine if he hadn’t).

Shoot ammo you know the origin of and is designed for use in your gun.

Shoot with a buddy.

Never forget to let your important people know you love them.

 

[MosinT53Hunter]

F*** says I.

takeaways:

Wear good Eye pro (imagine if he hadn’t).

Shoot ammo you know the origin of and is designed for use in your gun.

Shoot with a buddy.

Never forget to let your important people know you love them.

One more I would add to this:
If it feels like there is something wrong, check it out first before continuing to shoot.

 

[Hunter 08]

Here's Mark's video response.

What happened to Scott sucks. This wasn't a fault of the rifle, just poor ammo of questionable origin. Seems like his dad does majority of the filming? Glad he's alive and has a great morbid sense of humor.

I feel for Mark Serbu. If I built something like this that caused someone injury or untimely death, I'd be depressed too. Hopefully he can get some closure when he gets the rifle and the SLAP ammo Scott had to do a full investigation on it. Only good can come from this. The small amount of bashing I saw towards Mark was really unwarranted. Scott even said this was not fault of the rifle.

 

[Elkins45]

This picture tells me everything I need to know about the RN-50. That is significantly less than one full diameter of thread engagement for the breech plug. Even cast iron water pipe joints have more contact area than that and they only have to resist a few hundred psi max.

Hard pass. I know it was bad ammo, but I would want a better safety margin between me and ANY ammo.

 

[bat]

There's no requirement to test guns with proof loads in the U.S. although SAAMI does publish information for some cartridges for manufacturers that choose to do so.

The proof pressure for the 50BMG appears to be 65,000psi from what I can find which means that the 85,000psi figure from the video doesn't seem to be related to any official proof pressure.

I have a question about that point.
In France, we have the obligation of proofing any new firearm design, and any design changes. An then regular proofing are made in the manufacturer by the Official test bench picking a statistical sample of his production. (This mean you can have a perfectly brand new gun, who has been fired a couple time. ^^ Happens to me at least once!)

How do they make proof round? Very simply: they take manufactured round, or the rounds provided by the weapon maker in case of an exotic caliber for example, and... just stew theses rounds. At around 160°F for at least 24 hours, and then fire at least 2 rounds less than 3 minutes after the oven. This is the standard and legal procedure to make proof rounds. (at a side note, it mean if you store your ammo for example in your car under the sun for some time, maybe you will got proof ammo instead of normal ones!)

How US manufacturers make proof ammunitions?

 

[JohnKSa]

U.S. made guns are usually test fired, in my experience with new guns, but there's no legal requirement for the manufacturer to do proof testing with a proof (higher than normal pressure) round.

They just shoot them with standard pressure ammunition as a function test.

A manufacturer CAN proof test if they desire, but I'm not aware of any that claim they do (not that I've really looked for that information). Since there's no legal requirement to do so, there's also no established procedure for how to carry out the test or manufacture the round.

SAAMI does provide extensive recommendations for how to mark proof loads, pressures, etc., how to carry out the process but makes it clear that it's all voluntary.

To answer your question, US manufacturers who choose to proof test their firearms (assuming there are any) can do it any way they want with ammunition made any way they want since there's no binding standard for the process or for making the ammunition.

 

[Kano383]

What happened to Scott sucks. This wasn't a fault of the rifle, just poor ammo of questionable origin. Seems like his dad does majority of the filming? Glad he's alive and has a great morbid sense of humor.

I feel for Mark Serbu. If I built something like this that caused someone injury or untimely death, I'd be depressed too. Hopefully he can get some closure when he gets the rifle and the SLAP ammo Scott had to do a full investigation on it. Only good can come from this. The small amount of bashing I saw towards Mark was really unwarranted. Scott even said this was not fault of the rifle.

It's not about bashing anyone... It's not the rifle's fault, just like it's not the car's fault if a drunk driver hits you in a frontal collision. Yet, it makes a big difference to you if the car has seatbelts, airbags, and a collapsible steering column instead of having an old fashioned steel rod aimed right at your chest, with nothing to hold you back.

There is a big difference between building firearms, and designing firearms. You can be a very good builder, machinist, and metallurgist, but a poor designer - and vice versa.

Paul Mauser spent more than ten years refining his bolt action design, and still lost an eye after finalizing the K98, with one of his own designs blowing in his face (the C98 prototype, a semi-auto design). After that, he became really anal about safety...

John Browning also spent decades refining his designs, and produced a few very iffy models before ironing out some major safety issues.

Today, we have the advantage of more than a century of experience to draw upon, so there are no excuses for overlooking critical issues. The correct answer to safety is not "Overbuild it so it won't break/blow/fail", it's built-in redundancy, and safety mechanisms or features meant to avoid or minimize the consequences of a catastrophic failure.

 

[Casefull]

This picture tells me everything I need to know about the RN-50. That is significantly less than one full diameter of thread engagement for the breech plug. Even cast iron water pipe joints have more contact area than that and they only have to resist a few hundred psi max.

Hard pass. I know it was bad ammo, but I would want a better safety margin between me and ANY ammo.

View attachment 995938

You are absolutely right. My first thought in watching was that those threads are bound to weaken with each shot and over time they failed. It’s a very poor design, especially for long-term use. It wasn’t the ammo at all, the threads just failed. Lucky man.

 

[Hartkopf]

I would be researching if powder residue could be analyzed after that last shot. IMO, it was ten times the volatility of the previous rounds. If this happened because of improper storage of rounds loaded with the correct powder, then so be it. If pistol powder residue is found......... the reason needs to be found.
I’m not saying it was sabotage but damn.

 

[Bang!]

Analysis video that speaks to concerns mentioned so far. Statements on threads are interesting.

 

[Jim Watson]

While there is no proof law in the USA, if I were a member of SAAMI, or even if I weren't, I would certainly proof test my product guns in accordance with their procedures. That would give me some protection in a liability suit if one failed in use.

How do they make proof round? Very simply: they take manufactured round, or the rounds provided by the weapon maker in case of an exotic caliber for example, and... just stew theses rounds. At around 160°F for at least 24 hours, and then fire at least 2 rounds less than 3 minutes after the oven. This is the standard and legal procedure to make proof rounds. (at a side note, it mean if you store your ammo for example in your car under the sun for some time, maybe you will got proof ammo instead of normal ones!)

How US manufacturers make proof ammunitions?

How strange.
A SAAMI manufacturer may order proof loads (and pressure test reference ammunition) from whichever of the regular ammunition companies is contracted to provide it. Want to test your 7mm Brenneke? Just order up some stock number 81571P from Hornady.

Unfortunately, there is no SAAMI specification for .50 BMG. Army standard chamber pressures run from 54,000 psi to 59,000 psi. The High Pressure Test load is only 65,000 psi which is not a whale of a lot of safety margin over API, the hottest of the service loads.

 

[JCooperfan1911]

Of the following two men, which looks like they would design a safer gun?





I’ll go with option 2, thank you very much!

 

[Mk-211]

LOL

I think JMB would take that plumbing from him and then crack him over the head with it!

Then, if he didn't run off crying, might ask him if he wanted to learn something about firearms.

His stuff might not look as good as JMB's but his head is in the right frame of mind. There's nothing wrong with wanting to build a firearm or three, just go in the right direction. He also didn't build anything on the RN-50, Mark did all the early work and still does.

 

[Elkins45]

Analysis video that speaks to concerns mentioned so far. Statements on threads are interesting.

Interesting video, but I think he’s missing a point about the threaded length. He’s absolutely right that most of the load bears on the first four threads, but he (IMO) misses the point about a greater length of thread being able to act as a fail safe by providing a secondary bearing surface should the primary bearing threads fail.

He’s 100% on target about the need for a means of venting gas when a case fails.

 

[Double Naught Spy]

... It's not the rifle's fault,

And we know this because we have all done a metallurgical analysis of the rifle to make sure it was okay?

We can't know one way or the other at this point as to why the rifle failed.

You are absolutely right. My first thought in watching was that those threads are bound to weaken with each shot and over time they failed.

And I am sure hot gasses and corrosive powders also took their toll on those threads over time as well.

Analysis video that speaks to concerns mentioned so far. Statements on threads are interesting.

The video is really interesting. In addressing the number of threads, the speaker says extra threads would make no difference because the load is only carried on the first 4 threads and virtually none of the load is carried on the rest of the threads. While this may be true, it is only true so long as the first 4 threads remain intact. Loss of those threads would result in the load being transferred to other threads, if they were present. In other words, if only 4 threads are being engaged and the load is only carried on 4 threads, then there is no margin of safety or redundancy present.

edit: redundant comment, but it is a good point.

 

[bat]

The video is really interesting. In addressing the number of threads, the speaker says extra threads would make no difference because the load is only carried on the first 4 threads and virtually none of the load is carried on the rest of the threads. While this may be true, it is only true so long as the first 4 threads remain intact. Loss of those threads would result in the load being transferred to other threads, if they were present. In other words, if only 4 threads are being engaged and the load is only carried on 4 threads, then there is no margin of safety or redundancy present.

edit: redundant comment, but it is a good point.

No, additionnal threads would not prevent a catastrophic failure that already has exceeded the initials threads resistance, as the same causes results in same effects: failure of the threads under extreme pressure. Same threads, same pressure, same failure. (think of a cascading failure)

It may sound counter-intuitive that more thread add only marginally in the resistance and nothing in redundancy again an overpressure, but hey! Science!