50 Cal explodes

[hillsman]

This video is both shocking and impressive. The level of awareness and quick thinking is amazing.



Mods, please go ahead and delete this if it has already been shared.

[Shivaji.Dasgupta]

Yes I watched this one few days ago. This guy Was badly injured.

[pgupta]

It was a very trending video, they guy is lucky to be alive thanks to the quick thinking by his father.

[timmy]

I've had similar experiences with the 50 BMG's little brother, the 30-06. I was shooting some surplus 1942 ammo and had cases open up on me. Each fired case had a slot about 3- 4 mm long, longitudinally to the case, and about 0.5 mm wide. When fired, there was a blast of hot gasses that spewed something like chewing tobacco juice on the lens of my glasses (thank heavens I was wearing shooting glasses -- otherwise, I'd be "Long John Silver" now) and burning powder went into the skin of my face around the glasses. This was painful, but odd: I could feel individual grains burning in my skin.

I had very little shooting money at the time, which was the reason I was shooting this old surplus stuff, but it still was foolish of me to keep on shooting it. I shot up the lot and had 3 failures of the same time, with the same slot opened up in each case.

I still have a box of surplus 30-06, but it was made in 1935 and consists of four stripper clips in a box. It looks like new, but I have no intentions of shooting it. I don't even own a 30-06 anymore.

Usually, it is British-type ammo that has problems, due to the instability of cordite. It's common to find that hangfires and duds of various types, some of which can be dangerous, because they will push a bullet down the barrel and when the next round is fired, big troubles occur. This isn't good at all! Of all of the old surplus .303 ammo I've read about, POF seems to have the greatest number of duds.

I also have a fair quantity of Turkish 7.92x57 (8 mm Mauser) - maybe a thousand rounds. This stuff is quite hot and has a pronounced muzzle flash when it's touched off. It goes "bang" reliably (I may have had a dud or two, but can't recall) but the problem with this stuff is that the cases were improperly annealed, and a few of the rounds have cracks in the case necks.

Shooting this surplus stuff is chancy -- I've looked at old Kynoch cordite-loaded 577/450 for my Martini Henry, but it is notorious for going "pop" when the trigger is pulled, and given the price and the Berdan priming, I've always passed on it.

I've shot plenty of surplus Hungarian 7.62 x 54r ammo from the 70s, along with surplus from other countries. (including some from Albania, in brass cases, no less! It was the filthiest shooting stuff I've ever shot!) This was for old military rifle meets. I wanted to identify the most accurate surplus ammunition. Reloaded ammunition, in these competitions, put one up a class, and I preferred to shoot in the lowest class, which required surplus or commercially loaded ammunition. The Hungarian ammo turned out to be the best in my rifle, and showed no problems.

I've also got a fair stash of 7.62 x 25 Romanian that shoots just fine. I have read warnings about hot Czechoslovakian ammo meant for submachine guns, but have never come across it.

Shooting something big like this 50 BMG is something that, perhaps calls for a second thought beyond what would give to shooting "plain old" military surplus rifle ammunition. This video shows why: there's a lot of destructive power in a round this large, and one ought to consider the potential condition of the ammo that's used. For myself, I would stick to my own reloads in this example. Then, at least, I could tell what was in a reload. Yet, I do recognize the interest in shooting tracer rounds. (I'd never want to do it in any of my guns, as they are hard on the barrel.)

Anyway, the video is a good reminder of the need for thinking and caution, and the recognition of risk involved in our sport.

[winnie_the_pooh]

That is a nasty accident. I hope this acts as a lesson to all those who insist that old imported ammunition lasts for ever . Also that it is perfectly ok to fire even visibly damaged cartridges.

[Vikram]

I watched this video a while ago.

After watching this video, I was searching for information on the SLAP rounds.
I found this: "Never fire discarding saboted ammunition in any weapon fitted with a muzzle device, unless you KNOW it's been certified for that weapon. Sabots are intended to discard immediately upon exiting the muzzle, about where your choke, flash-hider, muzzle brake, etc. is located. This could cause the device to be physically ripped away from the weapon, become damaged or blocked (adversely affecting subsequent projectiles), or material may be thrown back towards the shooter or spectators. "
https://www.ammoguide.com/?article=kpagel0507
I wondered if this could this have been a reason why the gun exploded? However, the muzzle brake is still attached and there is no visible damage on the front end.
This page indicates that the pressure for the M903 SLAP round is 55,000PSI, which is in the same ballpark compared to the regular rounds.
https://www.inetres.com/gp/military/inf ... _ammo.html
Does this mean that it was a one-off round that was too hot? Could a stronger mechanism have prevented this mishap than the threaded cap used on this model?Your views please. Cheers.

[timmy]

Good points all, Vikram. The combination of the sabot and the muzzle break would be problematic, I think.

You also bring up a good point in that the failure could be expected to be at the muzzle brake if this was the problem in the video.

Your going down this path of reasoning makes me wonder about the way the chamber was cut: could the sabot have caught on the edge of the chamber?

Your questioning of the threaded cap is also interesting. We don't know the kind of engineering thought that went into this. I would note that the barrel is threaded (on this gun, I'm not sure, but assume so) into the receiver in the same fashion, so the method should be good, but the implementation is something we don't know about.

[timmy]

Here is a link to an article from the USA NRA, addressing low cost (relatively!) 50 BMG guns. The Serbu RN-50, which is the subject of the blow-up, is the last gun examined. Note that the Serbu RN-50 is a little more than half the price of the other "low-cost" rifles:

https://www.shootingillustrated.com/art ... mg-rifles/

Everyone is so afraid to post pictures that describe how the action of a firearm works. Perhaps they have more interest in gaudy finishes and gadgets, but here are the best pictures I could come up with:











My assessment of the Serbu RN-50 is as follows: I wouldn't describe this as a break-open action, as used in single and double barreled shotguns. The break-open aspect of the design enables the screw-on breech to be workable in a shoulder arm, giving access to the breech in a somewhat clumsy, but low cost way. The "ears" on the action couldn't, in my estimation, provide very much additional strength, if any. Rather, they probably serve as a safety feature that prevents closing the action unless the breech cap is securely and completely screwed down. There's nothing wrong with that. Additionally, because the hammer is mounted on the receiver, it is probably set up so that the hammer cannot contact the firing pin in the breech cap unless the barrel is completely locked into the receiver.

As I said, the action is clumsy, but its advantages lie in offering a rifle that accepts the powerful 50 BMG cartridge and is marketed at a low cost, relative to other 50 BMG rifles. I've examined other material on the web claiming that this rifle has no safety provisions, and frankly, I consider that material to be inaccurate and of little use. Because this post is a bit long to begin with, I'm not going to include any references to such material. No point is wasting time on someone's malarky!

My assessment of the incident, including two videos from the designer/maker, follows:

He's that close to death and he just laughs it off

I don't know about you guys, but to me, this is the definition of a fool, not a hero or a genius.

Guns blow up everyday, but it's not talked about

No statistics here, just an unsupported generalization. I call "rubbish" on this statement.

He mentions that people have been telling him by "private messages and emails" that even a Ma Deuce (a 50 BMG military issue machine gun) blows up -- is this the sum total of this guy's statistical analysis that he uses to design by, and back up his claims?

On a more facts and data basis, he mentions "detonation" as the cause, and that the round was "counterfeit." "Detonation" is the condition where pressure and chemical properties cause the powder to explode. We may think that a powder always explodes, but unless an anomaly takes place, POWDER NEVER EXPLODES, IT BURNS! The reason that there are so many powder formulations is to get different burn rate properties, which translate into different "pressure curves," graphs that show how the pressure in the chamber rises and falls as the powder burns. For instance, with a short barrel, one wants a powder that burns quickly, because powder burning after the bullet has exited the barrel does no good. (Actually, powders generally require a confined space to operate, as they require some amount of pressure to burn properly. Lay out some powder on the driveway and set it alight -- you probably shouldn't do this -- and you'll see an odd burning, but nothing like an explosion or fast burn as it occurs in the gun.)

A detonation will cause an explosion, a quick, uncontrolled burn that creates a very quick and very hight pressure rise that a gun's action doesn't handle well.

If this fellow has an explanation that doesn't depend on "awesome," "so much love," "a superman," or some other rubbish, it would be great to hear it. Otherwise, as you listen to this, ask yourself if you would want such a guy performing brain surgery on you: That will give you an idea about my opinion of this subject, whether the cartridge turns out to be the cause of the problem or not. My point here is that this guy addresses the issue of the gun blowing up without any mention of one technical fact, save for the mention of the word "detonation" with no supporting data whatsoever.

Here, several days later, The gunmaker/designer comes out with this video:



Now, here is a presentation that includes some facts and data, at last! Here, he addresses the strength of the screw-on breech cap design, which I raised in my original post. No math is presented, but the number his specialist comes up with is ~161,000 p/si. Not being an engineer or scientist myself, I don't have a way to verify this at hand, but have no intuitive reason to doubt such a figure. My only question here is, why was this figure arrived at after an accident? Should it not have been determined before the design passed to implementation? Designing and making something before having a firm technical basis for the design in the first place does not seem to be the mark of a good designer. It is, in fact, the sort of process where one's customers do one's quality control and engineering proof of concept work for them. That he did not go to his braintrust before the design went out tells me something! But, granted, this isn't the cause of the problem.

Second, his point about the counterfeit sabot in the cartridge is well-taken. This is not only with regard to the sabot itself, but his questioning how the round was loaded. It is a fact that, with some powders, a half load where the case is not filled to near capacity, but has significant air space, can create conditions ideal for detonation. Ball powders are one such powder -- when I started loading Winchester ball powder 296 in my Colt 45 (back in the early 80s), the warning against "light loading" was prominent in all load data. What the reloading data is for various powders in 50 BMG is, is not something I'm familiar with, however I'd suspect that the size of the case may introduce factors which differ from reloading, say, 30-06. Here, I'm certainly questioning the reloader's data, techniques, and expertise, which is justified by this fellow noting the lack of a crimp -- good evidence of a counterfeit reload. Recall, especially if you reload, that military ammo has crimped primers and crimped bullets to prevent a problem with primer and bullet seating in battlefield conditions, and where machine guns are involved. His point regarding the cartridge, in other words, is valid.

My conclusions:

1. So the bottom line is, is the gun safe? I think so, but I wouldn't be interested in shooting it myself. (I'm not interested in shooting any of this 50 BMG stuff, but it is a legal firearm and I'm foursquare in favor of 50 BMG's rights to shoot these things!)

2. I'm less than keen about shooting stuff that is designed by "seat-of-the-pants" designers like this, although I do recognize the fact that unsafe guns have come from large companies, as well. The firearms industry is in a constant state of flux due to market and legal issues, and it's not easy to keep abreast with all of the changes going on with new firearms. For instance, I might trust Ruger or Savage a little more than, say, Remington or Marlin to turn out a good gun (noting, of course, that older Marlins like my 39A 22 are made as well as anything one might wish for!), but my trust is still more centered on old military stuff and older guns like Colts, which have been proven over and over and have stood the test of time and battlefield.

3. Winnie's point regarding ammunition is well taken. I think good commercial ammunition is to be trusted. Military surplus is another issue. Someone else's reloads -- those, I would not and have never trusted at all. My own reloads, I do trust. I wouldn't have anyone else to blame, at least, in the case of failure.

[winnie_the_pooh]

Timmy, that is a very detailed analysis. A gun would fail at its weakest point. In this case it appears to be the threaded cap. Frankly,the entire rifle looks like a piece of plumbing. Perhaps there ought to be mandatory proof testing of firearms in USA rather than merely relying on the fear of manufacturers of being sued into bankruptcy ,to ensure that what they make is safe.

[KDS991213]

Timmy, that is a very detailed analysis. A gun would fail at its weakest point. In this case it appears to be the threaded cap. Frankly,the entire rifle looks like a piece of plumbing. Perhaps there ought to be mandatory proof testing of firearms in USA rather than merely relying on the fear of manufacturers of being sued into bankruptcy ,to ensure that what they make is safe.

Proof testing would not have helped in this case, to have 1.5 inch fine pitch thread sheared of like that would require insane amounts of pressure. And from the looks of it the round that caused the rifle to explode is loaded stupidly. He had fired dozens of those rounds & those previous ones didn't do any damage (or else he wouldn't be able to unscrew the cap) pieces of plumbing looking firearms can just be as reliable as normal looking firearms.

[Vikram]

Tim,

Excellent analysis and rational conclusions. Thank you for that.

Another gent who worked as a machinist for over 35 years said that he would be hesitant to shoot the rifle with the threaded cap. I have no expertise to either believe or disbelieve his opinion. It is an opinion, albeit borne out of his professional experience.

Mine is a purely instinctive reaction, not backed by an technical knowledge or experience. I watch a chap called Edwin Sarkissian on YouTube who shoots up things with sundry guns. One of them is this very Serbu model. It never inspired confidence in me though the chance of shooting with one may never come to me.

[timmy]

As I think about this, I picture a barrel screwed into a bolt action receiver. The receiver is essentially a tube, and on some rifles, it is made from a piece of seamless tubing. The barrel is threaded into the receiver in exactly the same way it is threaded into the cap of this rifle.

Now, in this rifle, the cap is made as one piece with the sides that have the threads. But in a bolt action rifle, the threaded tube is plugged by the bolt. I see a strong similarity here.

There are other guns that have an opposite arrangement: most muzzleloaders, for instance, have the inside of the barrel breech threaded and a plug is screwed in to the breech.

Artillery pieces using the Welin, Canet, and DeBange breaching system also have a breech plug (rather than a cap) that screws into the breech of the barrel.

I know that this looks like a water pipe or gas pipe with a cap on it, but I do believe that the application of this rifle is different. The weakness in the cap would be the point where the shape transitions from a cylinder to the round surface at the back -- where the steel's form turns in a 90* direction. But, the cap did not fail at this point -- the back was not blown off. Instead, the threaded part failed. This is the same sort of failure described by Frank DeHass in his "Bolt Action Rifles" book. When testing a Japanese Arisaka rifle with a cartridge loaded fully with Hercules 2400, he noted that the barrel appeared to have jumped out of the receiver by a thread.

Years ago, one of the pieces of junk a friend of mine had laying around his gun shop was a bolt from a Remington 788. All nine of its locking lugs had been sheared off, as well as the bolt handle (which serves as the safety lug). He said a reloader had fired the 788 and apparently gotten his powder mixed up. He lived and wanted to sue Remington for the failure. He brought the bolt to John to see whether his lawsuit might have any chance.

I'm not saying i'm right about this, but I don't think I'm wrong, either. I wouldn't care to shoot the thing, or any 50 BMG, as I said before.

[winnie_the_pooh]

The comment that the rifle looks like a piece of plumbing is not to say it is one. It is to point towards the rudimentary nature of the design. Apparently there is no thought towards the possibility of a catastrophic failure, even if it is due to the negligence of the shooter.

Ultimately,the rifle failed due to the shooter using suspect ammo. I am sure it is safe enough with proper ammunition.

[timmy]

Apparently there is no thought towards the possibility of a catastrophic failure, even if it is due to the negligence of the shooter.

There's no doubt about that, and I'd think that gas could escape around the firing pin and spray the shooter's face. People don't realize what the pressure of burning and expanding can do. For instance, when HMS Hood blew up in its famous battle with Bismarck, the pressure of the burning (not exploding) gasses lifted the aft pair of turrents and sent them flying -- thousands of tons into the air!

Many rifles, single shots especially, don't offer the shooter much in the way of protection from gasses. An M98 Mauser is a good example of a rifle that does: gasses that make their way around the firing pin are vented through large holes in the bolt body into the magazine. Also, in the military versions and the little-sporterized actions, the cocking piece sleeve fits like a flange over the rear of the action, blocking gas from traveling down the locking lug raceways and spraying the shooter's face. Mauser did a good job here, unlike even most other military actions of the day. Some bolt action military rifles did have gas holes in the receiver ring, at least.

For rifles like the rolling block, Martini-Henry, and break-open actions, for instance, there's no provision for gasses at all.

Not many of us think of gas handling when we consider a firearm, because case failures are not so common, thank goodness. But one never knows when it would be nice to have, like shooting glasses.

[Vikram]

This video provides a closer view at the gun that exploded.