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Link Posted: 4/29/2021 7:30:54 PM EDT
[#1]
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Quoted:
Whelp kiss the AK50 good bye. Whiteclaw will bitch out now.
View Quote


lol You really expected him to finish it?
Link Posted: 4/29/2021 7:44:45 PM EDT
[#2]
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Quoted:
The T-rex got him.
View Quote


It’s a velociraptor
Link Posted: 4/29/2021 7:50:01 PM EDT
[#3]
I’ve been posting in the comments section of some of his videos that I thought some of what he was doing was dangerous and that I thought he was going to get injured.

But it wasn’t from a gun exploding. I thought he was going to catch a ricochet from a handgun. I’ve seen handgun rounds bounce off of railroad ties like the ones he uses for a backstop.
Link Posted: 4/29/2021 7:59:56 PM EDT
[#4]
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Quoted:
50cal's scare the shit out of me honestly.
View Quote


I fired a Barrett bolt action and it was solid.
Link Posted: 4/29/2021 8:02:52 PM EDT
[#5]
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Quoted:


lol You really expected him to finish it?
View Quote

Of course not,but now he has a semi legitimate excuse not to do it.
Link Posted: 4/29/2021 8:13:14 PM EDT
[#6]
I don’t actively watch the YouTube’s so I’ve never heard of this guy but I watched this entire video. What a great job and quick thinking by him and his dad, and what an inspirational outlook on life that guy has. I’m so glad his faith in the lord has helped him to stay strong and optimistic during a trial that could easily ruin your life.
Link Posted: 4/29/2021 8:26:23 PM EDT
[#7]
As a suspicious old fart I have to wonder if these rounds that are so special and rare that the going rate is $100 a pop there is likely somebody out there faking it and cobbing  together counterfeit rounds.

The guy himself didn't seem so sure of the source of these rounds.

At any rate I am glad he was able to keep himself alive until he got to the good medical folks and apparently everything is on the heal.

One tough lucky guy!
Link Posted: 4/29/2021 8:30:51 PM EDT
[#8]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
I’ve been posting in the comments section of some of his videos that I thought some of what he was doing was dangerous and that I thought he was going to get injured.

But it wasn’t from a gun exploding. I thought he was going to catch a ricochet from a handgun. I’ve seen handgun rounds bounce off of railroad ties like the ones he uses for a backstop.
View Quote


I shoot against railroad ties with everything I own, including 22lr and I've never had anything bounce off. Rest assured that if a round fails to penetrate wood and bounces back it may sting, but wont carry enough energy to hurt you. Same with bowling pins.
Link Posted: 4/29/2021 8:48:56 PM EDT
[#9]
First off, I have not analyzed the gun design in this video nor do I have any professional association with Serbu Firearms. I admit to knowing Mark Serbu and we have discussed engineering/design on various gun projects (not this gun though) in the past.

So much misinformation about engineering and gun design in this thread.

  1. Almost all guns have threads at the highest pressure containing area, they are called barrel threads and they are usually between the barrel and the receiver or barrel extension. So when you say you would never shoot a gun with threads holding the pressure you are a dumb ass.
  2. Retiring a Rem 700 gun with 5000 rounds through a receiver that were "hot" is another dumb ass statement. You know how many Rem 700 actions have been rebarreled several times with it taking over 10K rounds to wear out a barrel usually? Your "hot" round flow the primers, head separation, and other high pressure signs?
  3. Proof pressure for a 50 bmg is 65000 psi (had to look this up on the internet since SAAMI does not list 50 bmg so it might be suspect), it is not 2x normal pressure.
  4. SLAP ammo has a bullet weight about 1/2 of the normal ball 50 bmg. The powder charge is very different that the normal load since it has to cycle a M2 HB with half the mass going down range. They had many problems designing the SABOT for the SLAP rounds and finding a suitable material for the SABOTs. The rounds that are on the surplus market are very questionable to start with and given the unknown storage, the material properties of the SABOT and powder should be suspect. They were never meant to be shout out of a Barret or any gun with a muzzle brake.
  5. Many guns have a safety factor less than 2. Yes this surprised the shit out of me since many other engineering industries (not including aerospace) prefer closer to 4 safety factors.
  6. As a gun owner/designer/engineer, 50 cal small arms scare the shit out of me. There is a shit load of energy in them and I have seen too many hurt by them. They also have a nasty habit of doing bad things to retinas.
  7. "Other guns have multiple safety features if the lugs fail" This is not true for many designs, specially since shot firearms. Rolling block, sliding breach, break open actions all typically have no method of containment other than the primary pressure containing component.
  8. Weight of a gun is the sign of a safe design, well the M2HB weights over 83lbs without tripod and there have been people gutted by them when they let lose. Design, not weight is the only quantitative measure of safety.
Link Posted: 4/29/2021 9:23:17 PM EDT
[#10]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Wow. To think the threads were cut clean from that steel cap.

He just used all of his 9 lives.
View Quote
yeah all three of them. fuck that. in general threads have to be as long as they are in diameter. those threads are maybe 1/4 the length of their diameter. hard pass. yes there was also some stamped steel lugs that are supposed to hold the cap on but yeah no.
Link Posted: 4/29/2021 9:33:38 PM EDT
[#11]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
As a suspicious old fart I have to wonder if these rounds that are so special and rare that the going rate is $100 a pop there is likely somebody out there faking it and cobbing  together counterfeit rounds.

The guy himself didn't seem so sure of the source of these rounds.

At any rate I am glad he was able to keep himself alive until he got to the good medical folks and apparently everything is on the heal.

One tough lucky guy!
View Quote


Per Mark Serbu over at WG:

"Obviously I'm going to be doing a video on this incident as soon as I get the blown-up rifle from Scott.  I think the culprit is counterfeit SLAP rounds, and that's pretty bad.  But I guess when they're selling for almost $200 each you're going to get opportunistic scumbags taking advantage of that.  As you can see in the pics the fake sabot (red) lacks the proper cuts and has a slightly different taper towards the front.  Also, the case is not crimped and the tungsten penetrator looks "wrong".  I would guess they either used pistol powder or something about that incorrect penetrator/sabot combination caused a momentary blockage that spiked the pressure.  Really bad day all around..."

Ammo that caused the Kaboom:


Genuine SLAP ammo ....pretty sure brown sabot is AP, red is Tracer. Notice the difference in the sabot material/design, and crimp.


Genuine 1991 Dated tracer....
Link Posted: 4/29/2021 9:42:19 PM EDT
[#12]
Discussion ForumsJump to Quoted PostQuote History
Quoted:


Per Mark Serbu over at WG:

"Obviously I'm going to be doing a video on this incident as soon as I get the blown-up rifle from Scott.  I think the culprit is counterfeit SLAP rounds, and that's pretty bad.  But I guess when they're selling for almost $200 each you're going to get opportunistic scumbags taking advantage of that.  As you can see in the pics the fake sabot (red) lacks the proper cuts and has a slightly different taper towards the front.  Also, the case is not crimped and the tungsten penetrator looks "wrong".  I would guess they either used pistol powder or something about that incorrect penetrator/sabot combination caused a momentary blockage that spiked the pressure.  Really bad day all around..."

Ammo that caused the Kaboom:
https://www.ar15.com/media/mediaFiles/55482/SLAP1-1923983.jpg

Genuine SLAP ammo ....pretty sure brown sabot is AP, red is Tracer. Notice the difference in the sabot material/design, and crimp.
https://www.ar15.com/media/mediaFiles/55482/SLAP2-1923988.jpg

Genuine 1991 Dated tracer....
https://www.ar15.com/media/mediaFiles/55482/slap3-1923990.jpg
View Quote View All Quotes
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Discussion ForumsJump to Quoted PostQuote History
Quoted:
Quoted:
As a suspicious old fart I have to wonder if these rounds that are so special and rare that the going rate is $100 a pop there is likely somebody out there faking it and cobbing  together counterfeit rounds.

The guy himself didn't seem so sure of the source of these rounds.

At any rate I am glad he was able to keep himself alive until he got to the good medical folks and apparently everything is on the heal.

One tough lucky guy!


Per Mark Serbu over at WG:

"Obviously I'm going to be doing a video on this incident as soon as I get the blown-up rifle from Scott.  I think the culprit is counterfeit SLAP rounds, and that's pretty bad.  But I guess when they're selling for almost $200 each you're going to get opportunistic scumbags taking advantage of that.  As you can see in the pics the fake sabot (red) lacks the proper cuts and has a slightly different taper towards the front.  Also, the case is not crimped and the tungsten penetrator looks "wrong".  I would guess they either used pistol powder or something about that incorrect penetrator/sabot combination caused a momentary blockage that spiked the pressure.  Really bad day all around..."

Ammo that caused the Kaboom:
https://www.ar15.com/media/mediaFiles/55482/SLAP1-1923983.jpg

Genuine SLAP ammo ....pretty sure brown sabot is AP, red is Tracer. Notice the difference in the sabot material/design, and crimp.
https://www.ar15.com/media/mediaFiles/55482/SLAP2-1923988.jpg

Genuine 1991 Dated tracer....
https://www.ar15.com/media/mediaFiles/55482/slap3-1923990.jpg


Ammo issue seems the most likely culprit.  The sheer magnitude of the explosion speaks for itself. That was no normal failure, even when considering it involved a 50BMG.
Link Posted: 4/29/2021 9:50:09 PM EDT
[#13]
Discussion ForumsJump to Quoted PostQuote History
Quoted:


Ammo issue seems the most likely culprit.  The sheer magnitude of the explosion speaks for itself. That was no normal failure, even when considering it involved a 50BMG.
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Quoted:
Quoted:
As a suspicious old fart I have to wonder if these rounds that are so special and rare that the going rate is $100 a pop there is likely somebody out there faking it and cobbing  together counterfeit rounds.

The guy himself didn't seem so sure of the source of these rounds.

At any rate I am glad he was able to keep himself alive until he got to the good medical folks and apparently everything is on the heal.

One tough lucky guy!


Per Mark Serbu over at WG:

"Obviously I'm going to be doing a video on this incident as soon as I get the blown-up rifle from Scott.  I think the culprit is counterfeit SLAP rounds, and that's pretty bad.  But I guess when they're selling for almost $200 each you're going to get opportunistic scumbags taking advantage of that.  As you can see in the pics the fake sabot (red) lacks the proper cuts and has a slightly different taper towards the front.  Also, the case is not crimped and the tungsten penetrator looks "wrong".  I would guess they either used pistol powder or something about that incorrect penetrator/sabot combination caused a momentary blockage that spiked the pressure.  Really bad day all around..."

Ammo that caused the Kaboom:
https://www.ar15.com/media/mediaFiles/55482/SLAP1-1923983.jpg

Genuine SLAP ammo ....pretty sure brown sabot is AP, red is Tracer. Notice the difference in the sabot material/design, and crimp.
https://www.ar15.com/media/mediaFiles/55482/SLAP2-1923988.jpg

Genuine 1991 Dated tracer....
https://www.ar15.com/media/mediaFiles/55482/slap3-1923990.jpg


Ammo issue seems the most likely culprit.  The sheer magnitude of the explosion speaks for itself. That was no normal failure, even when considering it involved a 50BMG.

I wonder if someone with a lathe and such was trying to make something that looked like a real one and screwed up the powder charge.
Link Posted: 4/29/2021 9:52:44 PM EDT
[#14]
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Quoted:
I don't see anything in common, please explain.
View Quote




V50


RN50


M99
Link Posted: 4/29/2021 10:02:50 PM EDT
[#15]
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Quoted:
Love the t-shirt at the end.
View Quote


I bought the t-shirt.

Never heard of the guy before this popped up, but I admire that he and his Dad remained collected and level headed if not calm, made good decisions and saved his life.

He’s going to have a hell of a medical bill and he still is offering a decent product in exchange for help with them.

I’ll toss him $30.

Besides, it’s the kind of shirt I like, people read it and go :”Huh?”

If you don’t know you don’t get it.

Maybe it will become the new “ just rub some dirt in it...”
Link Posted: 4/29/2021 10:02:57 PM EDT
[#16]
Link Posted: 4/29/2021 10:04:08 PM EDT
[#17]
Ban 50 caliber!
Link Posted: 4/29/2021 10:10:40 PM EDT
[#18]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
First off, I have not analyzed the gun design in this video nor do I have any professional association with Serbu Firearms. I admit to knowing Mark Serbu and we have discussed engineering/design on various gun projects (not this gun though) in the past.

So much misinformation about engineering and gun design in this thread.

  1. Almost all guns have threads at the highest pressure containing area, they are called barrel threads and they are usually between the barrel and the receiver or barrel extension. So when you say you would never shoot a gun with threads holding the pressure you are a dumb ass.
  2. Retiring a Rem 700 gun with 5000 rounds through a receiver that were "hot" is another dumb ass statement. You know how many Rem 700 actions have been rebarreled several times with it taking over 10K rounds to wear out a barrel usually? Your "hot" round flow the primers, head separation, and other high pressure signs?
  3. Proof pressure for a 50 bmg is 65000 psi (had to look this up on the internet since SAAMI does not list 50 bmg so it might be suspect), it is not 2x normal pressure.
  4. SLAP ammo has a bullet weight about 1/2 of the normal ball 50 bmg. The powder charge is very different that the normal load since it has to cycle a M2 HB with half the mass going down range. They had many problems designing the SABOT for the SLAP rounds and finding a suitable material for the SABOTs. The rounds that are on the surplus market are very questionable to start with and given the unknown storage, the material properties of the SABOT and powder should be suspect. They were never meant to be shout out of a Barret or any gun with a muzzle brake.
  5. Many guns have a safety factor less than 2. Yes this surprised the shit out of me since many other engineering industries (not including aerospace) prefer closer to 4 safety factors.
  6. As a gun owner/designer/engineer, 50 cal small arms scare the shit out of me. There is a shit load of energy in them and I have seen too many hurt by them. They also have a nasty habit of doing bad things to retinas.
  7. "Other guns have multiple safety features if the lugs fail" This is not true for many designs, specially since shot firearms. Rolling block, sliding breach, break open actions all typically have no method of containment other than the primary pressure containing component.
  8. Weight of a gun is the sign of a safe design, well the M2HB weights over 83lbs without tripod and there have been people gutted by them when they let lose. Design, not weight is the only quantitative measure of safety.
View Quote


You're complaining about misinformation?  Cite the incidences of people "gutted" by M2s and the failure rate.  I own a M2 (and a M107A1 and M82CQ).  M2 kabooms are not going to send the bolt through the chest cavity of the shooter. Nobody said that weight=safe alone, but if the inertia to resist a kaboom is the mass of a cap or small bolt, that makes them very good projectiles.  

Many guns do indeed have safety measures in case of a KB.  They range from bleed ports near the chamber, to top covers / receivers designed to minimize damage in case of a KB.  Nobody said ALL do.
Link Posted: 4/29/2021 10:11:53 PM EDT
[#19]
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Quoted:
Now you throw a Barrett in there, WTF?

None of them have anything in common other than being chambered for 50 BMG.

The Vulcan is a POS period!

The RN-50 is a solid design, I've shot one, have you?

The Barrett is a solid design also, I've shot them also.
View Quote


Reread the thread please
Link Posted: 4/29/2021 10:17:22 PM EDT
[#20]
As many have pointed out already:

Weak design without a failsafe.

4 threads actually engaged, on what 1 1/4" or 1 1/2" diameter?  How many threads would a machine nut of that diameter and thread pitch have?  What kind of dynamic load would that be designed to sustain?  How many fatigue cycles?

I see the fanboys are in here white knighting the design - guess what it failed.
And launched the cap into his eye, and fragmentation into his jugular.
You can make all the speculative excuses you want, but this is a firearm that fails lethally, at ~1.5x standard pressure.
Link Posted: 4/29/2021 10:19:15 PM EDT
[#21]
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Quoted:
Whelp kiss the AK50 good bye. Whiteclaw will bitch out now.
View Quote
Bruh, I laughed so hard.
Link Posted: 4/29/2021 10:55:08 PM EDT
[#22]
Quoted:

Almost all guns have threads at the highest pressure containing area, they are called barrel threads and they are usually between the barrel and the receiver or barrel extension.
So when you say you would never shoot a gun with threads holding the pressure you are a dumb ass.
View Quote



Except those barrel threads are on the opposite pressure side, away from the users face , the other is locked by a bolt / receiver.
The bolt and receiver typically will hold higher pressure and not fail before blowing a barrel or splitting it.


Barrels typically have a better thread fit class, more thread engagement and are not hand tightened.
Link Posted: 4/29/2021 11:22:21 PM EDT
[#23]
Link Posted: 4/29/2021 11:37:38 PM EDT
[#24]
I really like his content, glad he survived.   Bought a couple shirts.
Link Posted: 4/29/2021 11:39:13 PM EDT
[#25]
Discussion ForumsJump to Quoted PostQuote History
Quoted:



Except those barrel threads are on the opposite pressure side, away from the users face , the other is locked by a bolt / receiver.
The bolt and receiver typically will hold higher pressure and not fail before blowing a barrel or splitting it.


Barrels typically have a better thread fit class, more thread engagement and are not hand tightened.
View Quote View All Quotes
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Quoted:
Quoted:

Almost all guns have threads at the highest pressure containing area, they are called barrel threads and they are usually between the barrel and the receiver or barrel extension.
So when you say you would never shoot a gun with threads holding the pressure you are a dumb ass.



Except those barrel threads are on the opposite pressure side, away from the users face , the other is locked by a bolt / receiver.
The bolt and receiver typically will hold higher pressure and not fail before blowing a barrel or splitting it.


Barrels typically have a better thread fit class, more thread engagement and are not hand tightened.

Exactly.
Link Posted: 4/29/2021 11:43:37 PM EDT
[#26]
Drama llama
Link Posted: 4/30/2021 12:41:54 AM EDT
[#27]
Holy hell.
Link Posted: 4/30/2021 12:52:53 AM EDT
[#28]
Glad he made it. Long time subscriber and he’s an awesome guy. Had to order a shirt too.
Link Posted: 4/30/2021 12:59:48 AM EDT
[#29]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Glad to see he survived. One of my favorites for sure.

Did the sabot act as a muzzle obstruction? I was under the impression that sabots of any kind were a no-no with muzzle brakes.
View Quote


I was thinking maybe the sabot separated and caused a barrel obstruction also. Not sure how old the ammo was but if the sabot material broke down over time could have left obstruction.
Link Posted: 4/30/2021 1:52:58 AM EDT
[#30]
Discussion ForumsJump to Quoted PostQuote History
Quoted:


Everything has a safety margin, but how much is enough?   It would be fairly straight forward to identify the sheer strength of a thread lock versus a locking lug design.  It would be interesting to know how the two compare between something like the Serbu RN-50 (the gun in the video) and the Armalite AR-50.
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I didnt watch the entire thing but he remarks on it being a hot round... I really expect most 50s to be pretty over built. But I'm not surprised that something with that "royal nonesuch" guy's name exploded.


Mark Serbu

By all accounts it is a robust design.


Having the recoil be absorbed by nothing but those end cap threads seems more than a little suspect.  I wouldn't be too keen on trusting those even before seeing this video.

Isn't there a theoretical maximum pressure a given caliber can physically have, given powder types and case volume?  Why wouldn't they add a safety margin equal to that maximum?  The guy said normal 50 cal pressure is 55,000psi and that this round was probably 85,000psi.

I know over building has a cost but this guy almost died and by all accounts should have.


Everything has a safety margin, but how much is enough?   It would be fairly straight forward to identify the sheer strength of a thread lock versus a locking lug design.  It would be interesting to know how the two compare between something like the Serbu RN-50 (the gun in the video) and the Armalite AR-50.
Serbu typically proofs his weapons stupid high, well over industry standards. As for the screw cap, I remember watching one of his videos where he explained how he'd been surprised at how strong screw cap was. Something about having markedly mor surface contact than lugs.
Link Posted: 4/30/2021 2:06:36 AM EDT
[#31]
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Quoted:
No, Royal Nonesuch design, the kid who thinks headphones are earpro and builds pipe guns, sponsored by Mark Serbu
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Quoted:
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I didnt watch the entire thing but he remarks on it being a hot round... I really expect most 50s to be pretty over built. But I'm not surprised that something with that "royal nonesuch" guy's name exploded.


Mark Serbu

By all accounts it is a robust design.
No, Royal Nonesuch design, the kid who thinks headphones are earpro and builds pipe guns, sponsored by Mark Serbu

No. Royal Nonesuch concept, Mark Serbu design. He's made that clear on camera.
Link Posted: 4/30/2021 2:11:41 AM EDT
[#32]
Link Posted: 4/30/2021 2:22:37 AM EDT
[#33]
Discussion ForumsJump to Quoted PostQuote History
Quoted:


Video says it was likely 85ksi.  The design clearly needs to be enhanced but if it was built to handle 110ksi (2x safety factor) it would have been able to handle that load without grenading and sending lethal fragments into the operator as happened here.  Some damage yes, but not a catastrophic failure as demonstrated here.

50 caliber is an entirely different energy category from pistol and rifle calibers and should be treated as such.
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It's more or less understood in the engineering world that you build to 2x the anticipated stress.

Say a rifle cartridge generates 55kPSI. Build an action to withstand 110kPSI and it'll last forever. Build a residential electric transformer to handle 50KVA and it'll handle a 25KVA load practically forever. Build a revolver cylinder to withstand 80kPSI and it'll withstand 40kPSI practically forever.

But when you push pressures beyond that halfway point, you get on a sliding scale between 'lasts forever' and 'grenades on the next shot'. And it's really hard to predict the slope of that slide. It's entirely possible that the destruction in the OP video was the result of a single grossly overpressure shot, but it's also possible, and IMO more likely, that the rifle was being damaged by a series of overpressure shots, and the last one was the proverbial straw breaking the camel's back.



The problem here isn't the factor of safety.  This was so catastrophic that it looks the same would have happened even if it was built to handle 110ksi.  The problem is that the cheap design has no additional safeguards in the event of catastrophic failure.  

Because there is no large bolt, all that energy is directed to accelerating a small cap, which essentially becomes a very good projectile.  There is no receiver to contain the debris/projectile so it has a clear path to the shooter other than 2 small ears which also became projectiles.  None of this is true with a proper 50 BMG design from M99 to M107


Video says it was likely 85ksi.  The design clearly needs to be enhanced but if it was built to handle 110ksi (2x safety factor) it would have been able to handle that load without grenading and sending lethal fragments into the operator as happened here.  Some damage yes, but not a catastrophic failure as demonstrated here.

50 caliber is an entirely different energy category from pistol and rifle calibers and should be treated as such.

Please note the two very important words, "at least" in the text. Nobody knows at this point how overpressured that load was.
Link Posted: 4/30/2021 2:22:44 AM EDT
[#34]
I've heard stories of 30-06 slap rounds being dangerous as they can yaw before leaving the barrel.  I wonder if that applies to all slap rounds.
Link Posted: 4/30/2021 2:29:23 AM EDT
[#35]
Holy balls. With a slice like that across his neck I'm guessing he's damn lucky to be alive.
Link Posted: 4/30/2021 2:30:26 AM EDT
[#36]
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Quoted:


Sounds like someone was using spotter rounds in a semi.
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This one detonated in the magazine.  

The guy shooting said it was like having his hand crushed with a hammer.   He was fine.

https://photos.smugmug.com/Shooting/Organized-Gatherings/Upcoming-2014-APRC-Machinegun/i-j9WjKZP/0/cb25d605/L/20140517-GUNS3062-L.jpg


Sounds like someone was using spotter rounds in a semi.



What's a spotter round and why would it blow up in a semi?
Link Posted: 4/30/2021 2:35:33 AM EDT
[#37]
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Quoted:


Having the recoil be absorbed by nothing but those end cap threads seems more than a little suspect.  I wouldn't be too keen on trusting those even before seeing this video.

Isn't there a theoretical maximum pressure a given caliber can physically have, given powder types and case volume?  Why wouldn't they add a safety margin equal to that maximum?  The guy said normal 50 cal pressure is 55,000psi and that this round was probably 85,000psi.

I know over building has a cost but this guy almost died and by all accounts should have.
View Quote

There's a max pressure for in spec powder and projectile but you can easily dramatically exceed that.
Link Posted: 4/30/2021 2:37:38 AM EDT
[#38]
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Quoted:
Yeah, that guy is lucky.
Serbu build save firearms. This was more of a freak occurrence then the norm.
Firearms blow up all the time.
I don't doubt that Serbu will be dong a bit of modification to the design.
I've had conversations with Mr. Serbu on a firearm that is in the works. One based on the Russian PTRD-41. But in .50BMG. Bolt is S-7 and the receiver extension is 4140.
One aspect of the Russian design is that during recoil the bolt opens as the upper recoils back. It's buffered by a spring in the lower butt stock. Very clever design.
Mr. Sebu is no dummy but a very intelligent and knowledgeable man.
BTW, anybody know what holds the barrel to the receiver? Yep. Threads. So theoretically an overpressure round could blow the barrel out of the receiver. Which it probably has with soem rifle.
In any case as far as the RN-50 there is an 18 month wait for one.
So I guess a lot of dumb fucks are buying those cheap rifles.
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I've got one of these on my 'to buy' list. Even after watching the video. The design has been around for years and selling like crazy, but this is the first kaboom I've heard about. I'm not worried. OTOH, I now have a greater respect for the selection of safe ammo.
Link Posted: 4/30/2021 2:38:07 AM EDT
[#39]
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Quoted:



What's a spotter round and why would it blow up in a semi?
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Quoted:
This one detonated in the magazine.  

The guy shooting said it was like having his hand crushed with a hammer.   He was fine.

https://photos.smugmug.com/Shooting/Organized-Gatherings/Upcoming-2014-APRC-Machinegun/i-j9WjKZP/0/cb25d605/L/20140517-GUNS3062-L.jpg


Sounds like someone was using spotter rounds in a semi.



What's a spotter round and why would it blow up in a semi?

They have a charge in the bullet that goes off on impact. Originally designed to match the trajectory of a recoilless rifle so you weren't wasting the big rounds. Projectiles were available over the years and many people loaded them in 50 bmg and other rounds for fun.
Link Posted: 4/30/2021 2:51:38 AM EDT
[#40]
Glad he’s survived that... fucking crazy story if you haven’t watched the video.
Link Posted: 4/30/2021 2:55:04 AM EDT
[#41]
Holy shit, dude is lucky.

I've never fired a .50, and it's on my list of things to do.  But it'll probably be a one-and-done thing just to experience it.  

They definitely scare me a little, compared to just about all other small arms.
Link Posted: 4/30/2021 3:03:25 AM EDT
[#42]
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Quoted:


You're complaining about misinformation?  Cite the incidences of people "gutted" by M2s and the failure rate.  I own a M2 (and a M107A1 and M82CQ).  M2 kabooms are not going to send the bolt through the chest cavity of the shooter. Nobody said that weight=safe alone, but if the inertia to resist a kaboom is the mass of a cap or small bolt, that makes them very good projectiles.  

Many guns do indeed have safety measures in case of a KB.  They range from bleed ports near the chamber, to top covers / receivers designed to minimize damage in case of a KB.  Nobody said ALL do.
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Quoted:
Quoted:
First off, I have not analyzed the gun design in this video nor do I have any professional association with Serbu Firearms. I admit to knowing Mark Serbu and we have discussed engineering/design on various gun projects (not this gun though) in the past.

So much misinformation about engineering and gun design in this thread.

  1. Almost all guns have threads at the highest pressure containing area, they are called barrel threads and they are usually between the barrel and the receiver or barrel extension. So when you say you would never shoot a gun with threads holding the pressure you are a dumb ass.
  2. Retiring a Rem 700 gun with 5000 rounds through a receiver that were "hot" is another dumb ass statement. You know how many Rem 700 actions have been rebarreled several times with it taking over 10K rounds to wear out a barrel usually? Your "hot" round flow the primers, head separation, and other high pressure signs?
  3. Proof pressure for a 50 bmg is 65000 psi (had to look this up on the internet since SAAMI does not list 50 bmg so it might be suspect), it is not 2x normal pressure.
  4. SLAP ammo has a bullet weight about 1/2 of the normal ball 50 bmg. The powder charge is very different that the normal load since it has to cycle a M2 HB with half the mass going down range. They had many problems designing the SABOT for the SLAP rounds and finding a suitable material for the SABOTs. The rounds that are on the surplus market are very questionable to start with and given the unknown storage, the material properties of the SABOT and powder should be suspect. They were never meant to be shout out of a Barret or any gun with a muzzle brake.
  5. Many guns have a safety factor less than 2. Yes this surprised the shit out of me since many other engineering industries (not including aerospace) prefer closer to 4 safety factors.
  6. As a gun owner/designer/engineer, 50 cal small arms scare the shit out of me. There is a shit load of energy in them and I have seen too many hurt by them. They also have a nasty habit of doing bad things to retinas.
  7. "Other guns have multiple safety features if the lugs fail" This is not true for many designs, specially since shot firearms. Rolling block, sliding breach, break open actions all typically have no method of containment other than the primary pressure containing component.
  8. Weight of a gun is the sign of a safe design, well the M2HB weights over 83lbs without tripod and there have been people gutted by them when they let lose. Design, not weight is the only quantitative measure of safety.


You're complaining about misinformation?  Cite the incidences of people "gutted" by M2s and the failure rate.  I own a M2 (and a M107A1 and M82CQ).  M2 kabooms are not going to send the bolt through the chest cavity of the shooter. Nobody said that weight=safe alone, but if the inertia to resist a kaboom is the mass of a cap or small bolt, that makes them very good projectiles.  

Many guns do indeed have safety measures in case of a KB.  They range from bleed ports near the chamber, to top covers / receivers designed to minimize damage in case of a KB.  Nobody said ALL do.


Yeah, I can’t pull up the mishap reports but I’ve read them. M2HB’s do KB from time to time and blow a lot of stuff downwards into legs and abdomens. Hell, people are crying about threads and the
m2 doesn’t even lock shut except with a cam.
Link Posted: 4/30/2021 3:05:50 AM EDT
[#43]
Daaaaamn.  Finally watching the video.
Link Posted: 4/30/2021 3:38:17 AM EDT
[#44]
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Quoted:


Yeah, I can’t pull up the mishap reports but I’ve read them. M2HB’s do KB from time to time and blow a lot of stuff downwards into legs and abdomens. Hell, people are crying about threads and the
m2 doesn’t even lock shut except with a cam.
View Quote


Yep, a KB from a M2 will spray shards to legs and draw a little blood but nobody is getting "gutted".   There is a breech lock that moves up and down that holds the massive bolt in place though.
Link Posted: 4/30/2021 3:48:18 AM EDT
[#45]
lets see who passed strength of materials...

The video states mark serbu said the pressure must be over 85kpsi to blow the cap off which means he must test it to that pressure. Not that the round that went of was 85kpsi

The threaded cap design is quite safe and does indeed have more surface area than a regular lug design.

Someone mentioned torqueing the cap down. This does not matter in this case as long as the cap is not loose and the inherent design of the lock up will not allow it to close if the cap is loose. Do a calculation on thread shear strength and tell me where the torque value of the fastener is accounted for.

watching the weird stuff the previous rounds were doing i would guess some goobers own reloads.  I know sabot rounds are not accurate but that was something else.

heres an old post with gale mcmillan talking about shooting it out of a braked rifle
https://yarchive.net/gun/rifle/50bmg_sabot.html





Link Posted: 4/30/2021 3:53:09 AM EDT
[#46]
Jesus christ! Glad the dude is alive.
Link Posted: 4/30/2021 3:53:25 AM EDT
[#47]
Discussion ForumsJump to Quoted PostQuote History
Quoted:


Yep, a KB from a M2 will spray shards to legs and draw a little blood but nobody is getting "gutted".   There is a breech lock that moves up and down that holds the massive bolt in place though.
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There are 2 cases I know of with civilian M2HB guns at MG shoots where one was being fired from a standing position at a downward angle and caught shrapnel in the gut, the other was on a M3 mount and his legs extended under when it went shrapneling them.


As for your barrel thread comment, the AR15 threads hold the pressure in the same orientation as the 50 in question. Ever gun with a barrel extension pretty much are likewise.
Link Posted: 4/30/2021 4:10:03 AM EDT
[#48]
Discussion ForumsJump to Quoted PostQuote History


Im glad.scott survived, and im glad i saw the vid, but TFM is correct here.

He should have posted it to full30 or rumble.But i also know he needed the youtube exposure to sell the shirts that hes gonna need the money from to even put a dent in the hospital bills.

This is gonna fuck over mark surbu. Those tabs should have been full reciever length. I know not his fault but that would have prevented that.

Lesson learned. Exotic ammo is not to be fucked with when it can be counterfitted.

Shitty
Link Posted: 4/30/2021 4:13:43 AM EDT
[#49]
Discussion ForumsJump to Quoted PostQuote History
Quoted:

There are 2 cases I know of with civilian M2HB guns at MG shoots where one was being fired from a standing position at a downward angle and caught shrapnel in the gut, the other was on a M3 mount and his legs extended under when it went shrapneling them.


As for your barrel thread comment, the AR15 threads hold the pressure in the same orientation as the 50 in question. Ever gun with a barrel extension pretty much are likewise.
View Quote


That shrapnel was far from "gutting" a person.  Certainly not like sending a chunk of steel through a man's chest and into his lung like the RN50 did here.

Dust off that rusty engineering degree (or get a real one like I did) and look at the clamping force required for a 5.56 round vs a 50 BMG.  Also look at the surface area of both threads and take a guess at the shear stresses involved.  And on top of it all, dust off your English and realize I'm talking about additional safeguards with other guns.  If the lugs shear on a M99, it has to push a lot more mass and then it would have to shear the handle, and either penetrate the receiver or buttplate before ever touching the shooter.  The RN50 has no barrier other than little ears which only proved to be easily snapped and also become very good projectiles which lodged into the shooter's lung.
Link Posted: 4/30/2021 4:14:37 AM EDT
[#50]
I swear half of you didn’t even watch the video. It wasn’t the rifle.  It was the SLAP rounds of unknown origin/condition.
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