50 Bmg Blow up....

[...]

Ok, mark clearly must be creating accounts just to comment on his video.....no real person would fucking write this.

....there is no way these are not Mark Serbu.....

 

[AIAW]

Ok, mark clearly must be creating accounts just to comment on his video.....no real person would fucking write this.
View attachment 7624117


View attachment 7624119

....there is no way these are not Mark Serbu.....

Jesus. So where can I pay for farmed comments with BitCoin I wonder?

"Hottest factory rounds in production". Yeah, screw a bunch of CIP and SAAMI specs. What good are those anyhow!

P.S.: Never let Larry Thompson work on your shit.

 

[THEIS]

Hi,

I would point his legal team to update themselves on this...

https://www.hg.org/legal-articles/why-writing-fake-good-reviews-to-boost-your-business-may-be-illegal-38027

"Thank you handsome", lolololol is he hiring out of work showgirls to write reviews, lol?

Sincerely,
Theis

 

[Strykervet]

Wow...

It's kinda hard to overload one using US869 or equivalent because 240gr. of that about fills the case. The tolerance is also such that a bullet +/- nearly 100gr. isn't "that" big of a deal.

I've fired full power loads in an HTI but it's not fun and it's not really necessary so I limit to 220-210gr. The M2HB sorta needs full power shit to work right. And if it can blow that gun up, more power to 'em...

Most of that ammo is not factory shit. They're pulldowns. Some people use 20mm cannon powder because BMG powder is very hard (impossible) to come by. It varies a LOT. Sometimes it's even mixed or mislabeled altogether. I really think the intention isn't to load with it but to use it as an inexpensive filler in pyro applications. Anyway, it was enough variance that I bit the bullet and decided to load 10k rounds with 8lb. jugs of US869 instead of saving a few hundred by using 20lb lots of Vulcan powder and mixing to uniformity. Just didn't trust it. The guy selling it wasn't trying to blow smoke up my ass either and was honest about all this. I'm sure he was the exception to the rule. I'm also sure that by now he's more than sold out!

Besides that, H50 or similar could be substituted for US869 which is quite a bit hotter weight for weight, 210 vs. 240gr. if I'm not mistaken, for the same load.

Bottom line is don't do stupid shit with rounds the size of a hand grenade.

FWIW, I can manufacture a firearm that'll sufficiently fire 7.62 out of various gas pipe fittings... But it'd be fucking stupid to do so. That Serbu doesn't look a whole lot different than that.

 

[GrumpyOleFart]

I want that bloke to do it again, but set up the gopro first.
Love watching "fuck the specifications, what could possibly go wrong?"

 

[...]

"saved his life"

Shes followed his "creative ways"??

"Doing gods work".....well I guess god also destroyed Sodom and Gomorrah too sooooooo

I'm not saying you can pay for YouTube comments......buuuuuut you can pay for YouTube comments

Buy Youtube Comments Cheap at $2.99 | Custom / Random | BuzzVoice

BuzzVoice is the best site to buy Youtube comments from! Write your own comments for $3.99 or choose random positive comments for $2.99. Fast delivery.

buzzvoice.com

 

[sirhrmechanic]

Serbu... is this still a thing?

 

[AIAW]

 

[Doc68]

Hi,

I would point his legal team to update themselves on this...

https://www.hg.org/legal-articles/why-writing-fake-good-reviews-to-boost-your-business-may-be-illegal-38027

"Thank you handsome", lolololol is he hiring out of work showgirls to write reviews, lol?

Sincerely,
Theis

Hell, he already uses his daughter in his videos...

Doc

 

[Gommer]

Love those comments.

 

[earthquake]

Probably something they might want to remove from the website also...

View attachment 7623933

There are things in this world that you can simply look at and confidently boast "look at that build quality and attention to detail". It doesn't take a degree in mechanical engineering to look at that weapon and make judgement there.

SHTF 50 is another death magnet out there, along with Noreen. Not my personal opinion, it's proven fact.

View attachment 7623944

Umm, no thanks - I'm good! With a string for the YouTube views and good vibes, sure... I guess?

Can't tell from that photo, but where (if any?) are the gas venting holes or other safety features that would prevent this pipe bomb looking contraption from doing what it did to KB again?

 

[...]

Can't tell from that photo, but where (if any?) are the gas venting holes or other safety features that would prevent this pipe bomb looking contraption from doing what it did to KB again?

There are none, according to mark serbu, the RN50 doesn't need "secondary safety features"

 

[Im2bent]

Well at least the atf will make him put a serial number on the cap to keep us all safe.

 

[AIAW]

Can't tell from that photo, but where (if any?) are the gas venting holes or other safety features that would prevent this pipe bomb looking contraption from doing what it did to KB again?

There are orange plugs on both sides of the action, and also on the bolt body for venting gas. Of course nothing guarantees those will help in every type of situation, but it is a path to safely get that gas pressure vented.

Check out post 174 in this thread I linked below for an example of operation (and a missing pressure port from a ruptured case).

https://www.snipershide.com/shootin...e-actions-which-fails-more.40644/post-1016887

EDIT: Wait, you talking about the RN-50 or the AW-50?

The RN-50’s only safety feature - it’s $1200, who cares, just buy it!

 

[Aftermath]

What I find additionally frightening is that if you follow his latest vid to YT and look at the comments below, they are all glowing compliments for this guy, this gun, and his "analysis" of its safety, and his openness and transparency.

He HAS to be editing the comments and deleting those he doesn't have. Either that or, based on those comments, humanity is doomed due to abject congenital stupidity.

Definitely the latter

 

[earthquake]

There are orange plugs on both sides of the action, and also on the bolt body for venting gas. Of course nothing guarantees those will help in every type of situation, but it is a path to safely get that gas pressure vented.

Check out post 174 in this thread I linked below for an example of operation (and a missing pressure port from a ruptured case).

https://www.snipershide.com/shootin...e-actions-which-fails-more.40644/post-1016887

EDIT: Wait, you talking about the RN-50 or the AW-50?

The RN-50’s only safety feature - it’s $1200, who cares, just buy it!

I was talking about the RN-50.

 

[AIAW]

I was talking about the RN-50.

Oh yeah, nothing at all unfortunately. In fact, it’s probably relatively easy to replicate I would say.

 

[Im2bent]

Yo Marky here's a free upgrade idea. Make the cap click like a gas cap does to ensure its torqued properly....for safety.

 

[...]

Yo Marky here's a free upgrade idea. Make the cap click like a gas cap does to ensure its torqued properly....for safety.

or just do one of those capless fuel doors so there is nothing to fly back into the shooters face when it explodes

 

[Blackcreek]

Probably something they might want to remove from the website also...

View attachment 7623933

There are things in this world that you can simply look at and confidently boast "look at that build quality and attention to detail". It doesn't take a degree in mechanical engineering to look at that weapon and make judgement there.

SHTF 50 is another death magnet out there, along with Noreen. Not my personal opinion, it's proven fact.

View attachment 7623944

Umm, no thanks - I'm good! With a string for the YouTube views and good vibes, sure... I guess?

I'm not a welder but Damn that's a lot of undercut on that back weld. Looks like it was tig welded with no filler wire. I doubt that would pass a pipe welding test, forget about it being on something capable of producing 60,000 psi inches from your face

 

[Im2bent]

I'm not a welder but Damn that's a lot of undercut on that back weld. Looks like it was tig welded with no filler wire. I doubt that would pass a pipe welding test, forget about it being on something capable of producing 60,000 psi inches from your face

If you smoke a bowl before you start welding you don't need no stinkin filler.

 

[1500varmint]

for proper tread/attachment strength there is a specific torque value that the cap needs to be applied with, that’s mechanical engineering 101. It’s not just material strength.

Yeah, that was always the thing that made me most nervous watching people operate that gun. Unledd everyone uses a torque wrench when putting that cap on I'd presume that it's going to be tightened differently each time...

 

[Long_Action]

To get 160k + shear strength, you are factoring that the thread engagement is 1.5 times the circumference, and that the thread is properly torqued. Being in Tool and Die, I've seen a lot of failures and can tell you that the 2 lugs on the receiver would have been better off case hardened or soft. The fact that they sheared/broke off is very troubling. You can point all the fingers you want, but sometimes in manufacturing.... designs have flaws. It's how we get better/smarter as a Society. Not too long ago, drag racers were sitting on top of their top fuel transmissions. You learn from mistakes and move on....

 

[Gommer]

To get 160k + shear strength, you are factoring that the thread engagement is 1.5 times the circumference, and that the thread is properly torqued. Being in Tool and Die, I've seen a lot of failures and can tell you that the 2 lugs on the receiver would have been better off case hardened or soft. The fact that they sheared/broke off is very troubling. You can point all the fingers you want, but sometimes in manufacturing.... designs have flaws. It's how we get better/smarter as a Society. Not too long ago, drag racers were sitting on top of their top fuel transmissions. You learn from mistakes and move on....

Yeah, I think part of this is not just the fact a screw on cap for a 50BMG is a bad idea, nothing else behind it is a bad idea, but also screwing around with the chamber is a bad idea.

In a previous video he says that this company special made this rifle for him with a 'machine-gun' profile chamber, noting it was much looser. In the video he does describing all of the damage to himself and the parts that caused it -- I heard no mention of where the casing was. Being that it was not in his face or neck -- I'm inclined to think that chamber was so loose the pressure went around the casing instead of the casing itself being part of the chamber.

That's just a thought.

 

[...]

To get 160k + shear strength, you are factoring that the thread engagement is 1.5 times the circumference, and that the thread is properly torqued. Being in Tool and Die, I've seen a lot of failures and can tell you that the 2 lugs on the receiver would have been better off case hardened or soft. The fact that they sheared/broke off is very troubling. You can point all the fingers you want, but sometimes in manufacturing.... designs have flaws. It's how we get better/smarter as a Society. Not too long ago, drag racers were sitting on top of their top fuel transmissions. You learn from mistakes and move on....

so 1.5-12 threads at 1.5x thread engagement would give us 2.25" of thread required.....or 27 threads

mark had 4-5 threads.....or about .33-42"

 

[brianf]

I was going to post the same a day or so ago but it’s almost not worth it.

He doesn’t know the difference

Everything we are explaining will only give him a better product...when he should be closing his doors

 

[CMP70306]

I was going to post the same a day or so ago but it’s almost not worth it.

He doesn’t know the difference

Everything we are explaining will only give him a better product...when he should be closing his doors

Based on what I’ve seen I think you are giving the man far too much credit.

 

[Mordamer]

I am a mechanical engineer so this stuff interests me. In my experience, well done back of the envelope calculations will get an answer that is in the general ball park of the truth. Here is my attempt at a back of the envelope calculation to determine the amount of chamber pressure it takes to shear the threads.

Assumptions:
1. Barrel steel that is quoted as "30 Rockwell C" has an ultimate tensile strength of 148 ksi.
2. Shear strength is ~60% of ultimate tensile strength so let's assume 89 ksi shear.
3. Assume the case head fails and that the gas impinges on a surface area on the threaded cap that is about the same as the thread max diameter so 1.5 inches round. So an area of 1.77 inches squared.
4. A total of 4 threads failed under shear load.

The threads have a root width of .068" and a root diameter of 1.38" then one thread has a root area of .295 inches squared. 4 threads together have a total root area 1.18 inches square.

The equation to satisfy should be:

(Chamber pressure)*(surface area of the cap)=(shear strength)*(root area of the threads)

Solving for chamber pressure I get ~59,000 PSI to make the threads fail. This is only if the case head fails and gas impinges on the full rear surface area of the cap.

If the case doesn't fail and only the case head is pressing rearward on the cap I get a pressure in the case of 208,000 PSI to make the threads fail.

In one of the pictures of the barrel in Mark's video you can clearly see the rest of the case left in the chamber. A classic case head separation is what it looks like to me.

These calculations would only be the start of determining if a design was feasible. A good 3D modeling program with built in FEA would be the next step. If anyone sees a glaring error please point it out and I'll edit the post.

 

[LeftyJason]

I am a mechanical engineer so this stuff interests me. In my experience, well done back of the envelope calculations will get an answer that is in the general ball park of the truth. Here is my attempt at a back of the envelope calculation to determine the amount of chamber pressure it takes to shear the threads.

Assumptions:
1. Barrel steel that is quoted as "30 Rockwell C" has an ultimate tensile strength of 148 ksi.
2. Shear strength is ~60% of ultimate tensile strength so let's assume 89 ksi shear.
3. Assume the case head fails and that the gas impinges on a surface area on the threaded cap that is about the same as the thread max diameter so 1.5 inches round. So an area of 1.77 inches squared.
4. A total of 4 threads failed under shear load.

The threads have a root width of .068" and a root diameter of 1.38" then one thread has a root area of .295 inches squared. 4 threads together have a total root area 1.18 inches square.

The equation to satisfy should be:

(Chamber pressure)*(surface area of the cap)=(shear strength)*(root area of the threads)

Solving for chamber pressure I get ~59,000 PSI to make the threads fail. This is only if the case head fails and gas impinges on the full rear surface area of the cap.

If the case doesn't fail and only the case head is pressing rearward on the cap I get a pressure in the case of 208,000 PSI to make the threads fail.

In one of the pictures of the barrel in Mark's video you can clearly see the rest of the case left in the chamber. A classic case head separation is what it looks like to me.

These calculations would only be the start of determining if a design was feasible. A good 3D modeling program with built in FEA would be the next step. If anyone sees a glaring error please point it out and I'll edit the post.

NERD!!!!!



Just messing with you. I work as a machinist. Son of a chemical engineer. I should go to school to be either a mechanical engineer or manufacturing engineer.

 

[AIAW]

Looks like testing has started on their 375 CT model.

 

[Im2bent]

Looks like testing has started on their 375 CT model.

View attachment 7624760

Looks like a tack driver. KO2M here I come...lulz

 

[THEIS]

Looks like a tack driver. KO2M here I come...lulz

Hi,

Better quieten down on that....you will get blamed for no manufacturers/companies/people in the ELR sector of the industry coming on SH, lolol

Sincerely,
Theis

 

[Sean the Nailer]

Looks like testing has started on their 375 CT model.

View attachment 7624760

I heard that this version was gonna be a muzzle-loaded, smokeless powder, matchlock system. Due to the pesky primer shortage and all the 'forward thinking' involved in development.

And they're advancing protoypes in the flechette division....

 

[Numedal]

I am a mechanical engineer so this stuff interests me. In my experience, well done back of the envelope calculations will get an answer that is in the general ball park of the truth. Here is my attempt at a back of the envelope calculation to determine the amount of chamber pressure it takes to shear the threads.

Assumptions:
1. Barrel steel that is quoted as "30 Rockwell C" has an ultimate tensile strength of 148 ksi.
2. Shear strength is ~60% of ultimate tensile strength so let's assume 89 ksi shear.
3. Assume the case head fails and that the gas impinges on a surface area on the threaded cap that is about the same as the thread max diameter so 1.5 inches round. So an area of 1.77 inches squared.
4. A total of 4 threads failed under shear load.

The threads have a root width of .068" and a root diameter of 1.38" then one thread has a root area of .295 inches squared. 4 threads together have a total root area 1.18 inches square.

The equation to satisfy should be:

(Chamber pressure)*(surface area of the cap)=(shear strength)*(root area of the threads)

Solving for chamber pressure I get ~59,000 PSI to make the threads fail. This is only if the case head fails and gas impinges on the full rear surface area of the cap.

If the case doesn't fail and only the case head is pressing rearward on the cap I get a pressure in the case of 208,000 PSI to make the threads fail.

In one of the pictures of the barrel in Mark's video you can clearly see the rest of the case left in the chamber. A classic case head separation is what it looks like to me.

These calculations would only be the start of determining if a design was feasible. A good 3D modeling program with built in FEA would be the next step. If anyone sees a glaring error please point it out and I'll edit the post.

I may be thinking incorrectly (pretty tired atm) but wouldn't this be the case assuming the failure was by the threads stripping? Haven't studied the pictures in detail but seem to remember the ones I saw looking more like the threaded area sheared off in the valley of one of the threads (point of minimum material cross section).

 

[Mordamer]

I may be thinking incorrectly (pretty tired atm) but wouldn't this be the case assuming the failure was by the threads stripping? Haven't studied the pictures in detail but seem to remember the ones I saw looking more like the threaded area sheared off in the valley of one of the threads (point of minimum material cross section).

I'm not sure what the difference is between the threads "stripping" and the threads shearing off at the root. The threads certainly sheared off at the root which is the point of maximum thickness.

 

[Long_Action]

If the rifle is truly safe, Mark should put a squib round in front to the chamber and then load a round. Get behind the gun and shoot it. If he does this then 1400 gun owners can have faith in their guns. This should have been done in the first place!

 

[Numedal]

I'm not sure what the difference is between the threads "stripping" and the threads shearing off at the root. The threads certainly sheared off at the root which is the point of maximum thickness.

Like I said, my brain isn't firing on all cylinders at present. Either I mis-thought or not awake enough to put my thoughts properly in writing. Will try again in the morning...

 

[LeftyJason]

I may be thinking incorrectly (pretty tired atm) but wouldn't this be the case assuming the failure was by the threads stripping? Haven't studied the pictures in detail but seem to remember the ones I saw looking more like the threaded area sheared off in the valley of one of the threads (point of minimum material cross section).

I'm not sure what the difference is between the threads "stripping" and the threads shearing off at the root. The threads certainly sheared off at the root which is the point of maximum thickness.

Like I said, my brain isn't firing on all cylinders at present. Either I mis-thought or not awake enough to put my thoughts properly in writing. Will try again in the morning...

Mordamer I think you are talking about threads shearing off at the rood like the left side mark.

Numedal I think you are thinking it would rip like the mark on the right side through the valley.

 

[THEIS]

View attachment 7625481

Hi,

Is that their new QD barrel extension for the CheyBoom??

Sincerely,
Theis

 

[KZP]

Hi,

Is that their new QD barrel extension for the CheyBoom??

Sincerely,
Theis

That's the chamber extension to shoot 20mm ammunition.

 

[LeftyJason]

Hi,

Is that their new QD barrel extension for the CheyBoom??

Sincerely,
Theis

No. Thats the aftermarket. This is the one for the CheyBoom.

 

[LeftyJason]

That's the chamber extension to shoot 20mm ammunition.

Still incorrect. This is the extension. Built in shear lines.

 

[KZP]

Still incorrect. This is the extension. Built in shear lines.
View attachment 7625503

I'm pretty sure that is the chamber insert to adjust throat depth for slap rounds.

 

[Numedal]

Mordamer I think you are talking about threads shearing off at the rood like the left side mark.

Numedal I think you are thinking it would rip like the mark on the right side through the valley.
View attachment 7625481

Indeed what I was thinking

 

[Easa]

There is an update from Serbu himself.

 

[Whiskey_Tango6.5]

KB shoulda sent the scope back to Vortex.

 

[...]

There is an update from Serbu himself.

I refuse to believe this man has an engineering degree.....just listening to him speak it is clear he has 0 understanding of materials science or engineering physics......

This dude is 1 step away from will Hayden, all he's missing is a child rape charge.

In any event, this dudes retardation is proving to be a great source of lecture material on engineering ethics and product design for my classes.

 

[Baron23]

Wow, he goes on and on about the fact that the breech cap was essentially undamaged, made of hard alloy, hardened...yada, yada, yada....then just kind of skips over the entirely flattened threads.

Just wow.

 

[THEIS]

Hi,

Geezus Christ......he really just needs to stop and seek external advise and assistance from forensic firearm specialist along with failure analysis engineers.

Sincerely,
Theis

 

[Strykervet]

There's an old army FM on how to make field expedient weapons out of gas pipe that will chamber common military rounds.

But none of them chamber a .50. There's a reason for that.

Yeah, fuck Barret, AW and DTA, who needs bolt lugs?

And that's not a "case head separation" --that essentially severs the case into two pieces at the thin part left from swaging the brass.

That looks like to me where the primer failed first due to weak support allowing the rest to just blow out along with it. What a SHITTY design, and this fucktard, it's obvious he has no idea.

For sure someone has seen this now and contacted an attorney. I can tell you I'd be Serbu's new owner if that happened to me. Fact. Not there'd be much worth salvaging, if he had CNC shit he wouldn't be making this garbage I'm sure. Engineering degree or not, that's the kind of shit I'd make if I was still 12yo...