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Quoted: 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. View Quote Nah, fam. It was a shitty threaded design that a mechanical engineer designed and tested for its intended purpose. Don’t try to defend the logical conclusion that it was some jacked up, bootleg SLAP ammo because you’ll just sound like a fag and your shit will be all retarded. |
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Quoted: 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. View Quote You miss the point, the ammo was the problem, yes. But the rifles design did nothing to mitigate danger to the shooter in the event of a failure. If shit explodes the rifle should also have a way to push the energy away from the shooter. |
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Quoted: You miss the point, the ammo was the problem, yes. But the rifles design did nothing to mitigate danger to the shooter in the event of a failure. If shit explodes the rifle should also have a way to push the energy away from the shooter. View Quote Im in the sketch ammo is at fault camp but yes those ears becoming shrapnel was definitely not accounted for. From the pics they need to be double in length to withstand the 85kpsi that the design is tested to. But i dont think there were ever meant for that, just as a check to keep the rifle from closing if the cap is not seated. |
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working age limit...I am in the process of retiring a rem 700 action because nobody has ever been able to tell me what the life expectancy of the bolt lugs are at 65,000 psi, View Quote |
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Quoted:
As many have pointed out already: Weak design without a failsafe. View Quote View All Quotes View All Quotes You can make all the speculative excuses you want, but this is a firearm that fails lethally, at ~1.5x standard pressure. That being said, I think the comment on multiple overloaded rounds holds merit. Who knows what the PSI was on any of the sketchy rounds, and each one potentially contributed to the subsequent failure. Reality is, every design has a failure point, and some have built in redundancies...I'm not sure any of them would have held the pressure of these rounds. |
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Quoted: 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. View Quote I is not an engineer, but I thought this was the case. Torque on threads does not increase their strength. |
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Quoted: Lol. I'm not sure there is a shoulder fired .50 that wouldn't have severely injured the shooter with the ammo. Your whole assumption is incorrect. There is absolutely now way of knowing what the PSI was on the round that destroyed the rifle. Period. The video clearly states that according to Serbu, the threading is sufficient to at least 85k PSI....meaning, this was over 85k psi. That being said, I think the comment on multiple overloaded rounds holds merit. Who knows what the PSI was on any of the sketchy rounds, and each one potentially contributed to the subsequent failure. Reality is, every design has a failure point, and some have built in redundancies...I'm not sure any of them would have held the pressure of these rounds. View Quote View All Quotes View All Quotes Quoted: Quoted: As many have pointed out already: Weak design without a failsafe. Lol. I'm not sure there is a shoulder fired .50 that wouldn't have severely injured the shooter with the ammo. You can make all the speculative excuses you want, but this is a firearm that fails lethally, at ~1.5x standard pressure. Your whole assumption is incorrect. There is absolutely now way of knowing what the PSI was on the round that destroyed the rifle. Period. The video clearly states that according to Serbu, the threading is sufficient to at least 85k PSI....meaning, this was over 85k psi. That being said, I think the comment on multiple overloaded rounds holds merit. Who knows what the PSI was on any of the sketchy rounds, and each one potentially contributed to the subsequent failure. Reality is, every design has a failure point, and some have built in redundancies...I'm not sure any of them would have held the pressure of these rounds. If the threads failed at 85k, which per the designer is the failure point, then that was the maximum pressure achieved. Pressure was released at that point. How much pressure would that round have built in a stronger gun? Who knows, and irrelevant. I’m also suspicious of a number given over the phone without an analysis of the failing parts. 85k may be the design pressure, which IMO still makes it a crap gun since it fails lethally, but this gun may have had a manufacturing defect and/or fatigue that caused it to fail at 55k on that particular shot. Shallow threads on the cap or barrel, bad heat treat on the barrel, etc. |
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Wow, that's gnarly.
I enjoy the discussion going on here though. I agree that one shouldn't shoot SLAP rounds, and also that the gun is basically not a problem in any realistic use case. I don't fault Serbu for KB's injuries here: why should the ears be manufactured to withstand insane forces when the thread cap already withstands failures with an appropriate safety margin? If designers had to anticipate every failure case you'd end up with incredibly clunky and expensive firearms. Should every rifle designer anticipate shooters putting a compressed titegroup load through their gun? I guess at its root it's a discussion of safety margins. |
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Quoted: buying a high quality expensive rifle on the cheap, is a lot different than buying a cheap quality rifle cheap. the ar50 is built like a tank, and probably weighs almost 2x what that rifle does. which is a lot of extra steel. serbu 50 = 18lbs ar50 = 34lbs imho its like comparing a light weight taurus / smith 357 mag and a ruger super redhawk 357 mag. the smith / taurus might shoot 357 mag safely, but the ruger will safely handle loads that will grenade the smith / taurus. that rifle in the story might well have had a load that would have grenaded any 50 rifle, but the comparison is still sound, some are just a lot stronger than others, and the serbu is definately on the low end of the strength scale, when compared to other rifles. View Quote |
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Is the Kaboom in the video? If so, at what time? I don’t feel like watching it all
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Oh nonsense. Load up your favorite 30-06 full to the brim with Bullseye. And a 250 gr. bullet. Then sit behind the rifle and keep firing those super rounds. Good luck. Oh, add a magnum primer for sure fire results too.
The RN-50 was designed to standard .50 BMG pressures. As is any other .50 BMG. With the safety margin figured in. Take your wonderful Barrett and keep shooting suspect ammo in it. Sooner or later it will fail. And rifle bolts do exit the receiver. BTW, how many of the vaunted AR15 bolts have sheared the bolt lugs and were launched backwards. |
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I hadn't seen that design before seeing this video.
Wow. Not sure you could pay me to shoot that, honestly. |
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What pressures would a full case of Blue Dot see in a 50 BMG?
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Quoted: I is not an engineer, but I thought this was the case. Torque on threads does not increase their strength. View Quote View All Quotes View All Quotes Quoted: Quoted: 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. I is not an engineer, but I thought this was the case. Torque on threads does not increase their strength. Pretension torque does, however, increase thread engagement due to the slight deformation. If the threads are only marginally tightened and the material is somewhat brittle, then only one or two threads might support the load instead of sharing the load evenly, leaving to a cascading thread failure. The pressure required to shear one thread in that design isn't very much if the pressure penetrates into the back of the breech. To answer the other guy's question, torque in a bolted joint (quite different from this situation, where the threads are essentially directly loaded) does actually substantially reduce the load experienced by the threaded fastener after installation, provided that the fastener is thereafter indirectly loaded through the joint itself, and the joint is never sufficiently loaded to the point of separation, as it becomes a strain-based compatibility condition instead of a stress-based one. |
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Quoted: As pointed out earlier, have you ever shot an AR-15? If you have, you have "shot that design". View Quote View All Quotes View All Quotes Quoted: Quoted: I hadn't seen that design before seeing this video. Wow. Not sure you could pay me to shoot that, honestly. As pointed out earlier, have you ever shot an AR-15? If you have, you have "shot that design". Compare the shear area, fit/engagement and effective pressure area in an ar-15 bolt and the failure modes and effects from a sheared lug in that design to those in this design. Incorrect. |
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Quoted: As pointed out earlier, have you ever shot an AR-15? If you have, you have "shot that design". View Quote View All Quotes View All Quotes Quoted: Quoted: I hadn't seen that design before seeing this video. Wow. Not sure you could pay me to shoot that, honestly. As pointed out earlier, have you ever shot an AR-15? If you have, you have "shot that design". Yeah and we’ve all shot blowback 22s and break open shotguns too. So a blowback 50BMG should be good to go! Never mind AR locking lugs aren’t threads. |
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Quoted: Oh nonsense. Load up your favorite 30-06 full to the brim with Bullseye. And a 250 gr. bullet. Then sit behind the rifle and keep firing those super rounds. Good luck. Oh, add a magnum primer for sure fire results too. The RN-50 was designed to standard .50 BMG pressures. As is any other .50 BMG. With the safety margin figured in. Take your wonderful Barrett and keep shooting suspect ammo in it. Sooner or later it will fail. And rifle bolts do exit the receiver. BTW, how many of the vaunted AR15 bolts have sheared the bolt lugs and were launched backwards. View Quote Sure, something gives. Point is what happens. Chances are your hands will catch some shrapnel. Are you going to eat a large piece of steel straight to the face? Probably not. That's the difference. Find me an incident where someone ate a Remington 700 bolt? |
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Quoted: 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 View Quote View All Quotes View All Quotes Quoted: Quoted: 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 This. This is a cheap homemade design by someone who doesnt know what he is doing, and doesnt understand safety. Most every modern gun takes into account the possibility of a Kaboom, and engineers it such that the Kaboom doesn't kill the operator. This design though blows out the screw cap which shears the guide ears, all of which come back at the operators face. An AR Kaboom or Garand Kaboomz or almost any other gun Kaboom, would never fail in such a lethal manner. When he showed that cap hitting his glasses like that, I was like Holy Shit- he's lucky to be alive and still his vision from that alone. When he said, then it gets worse - I was like: what can get worse then that? Then he showed what happened with the Ears, that are just sitting there as part of the design. And how those basically turned into .22 bullets at .22 power, coming at his face. The dude took a .22 neck shot into his jugular. I"m still not sure how the F he lived thru that. If he didnt have support help there that knew what they were doing, no way would he have lived. Holy Shit Maybe I'll just sorta take .50 cal off the dream list, because that was some F'ing terrifying shit. |
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1.5 safety factor on a threaded cap that holds in the explodey forces and is pointed at your face? Mark Serbu is a moooooooroooooooon
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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 View All Quotes View All Quotes Quoted: Quoted: Quoted: 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. If 55ksi is the max allowable pressure 85ksi is the margin. Serbu is saying the rifle is proofed to 85ksi, not that you should be fine to hit that on every shot. 55ksi is a normal BMG pressure. |
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Quoted: This seems....excessive. If you are that concerned, and I am not sure why you would be, why not simply replace the bolt (where the lugs are located)? View Quote Since most people can't get a 300rum barrel to live thru more than 800 rounds sub moa, and the fact that all steel has a stress/cycle life, and knowing this rifle spent most of its life shooting the original factory 180/3250fps ammo,(long ago detuned to 180/3200by Remington) it has been living on the edge its entire life, I see no reason to keep pushing it, especially since if I died tomorrow one of my kids would get it, and they would have no clue about action life expectancy...sure I could throw a new bolt in it, along with more smith labor, but seems like a waste of money considering the price of a tenacity action...which also eliminates sending the action stateside every time it needs a new barrel...at close to 200 bucks shipping round trip...Oh and most quality smiths are 8-12 months out for any work....swapping actions was an easy choice... |
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Quoted: This seems....excessive. If you are that concerned, and I am not sure why you would be, why not simply replace the bolt (where the lugs are located)? View Quote View All Quotes View All Quotes Quoted: working age limit...I am in the process of retiring a rem 700 action because nobody has ever been able to tell me what the life expectancy of the bolt lugs are at 65,000 psi, This seems....excessive. If you are that concerned, and I am not sure why you would be, why not simply replace the bolt (where the lugs are located)? I can’t even get my head around that statement. Retiring a bolt action? |
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Quoted: Maybe I'll just sorta take .50 cal off the dream list, because that was some F'ing terrifying shit. View Quote 50 guns and ammo are expensive but it’s pretty cool to have one in the collection. With factory ammo and a decent design (Barrett) I don’t know if it’s much more dangerous than driving or being obese. |
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Quoted: Oh nonsense. Load up your favorite 30-06 full to the brim with Bullseye. And a 250 gr. bullet. Then sit behind the rifle and keep firing those super rounds. Good luck. Oh, add a magnum primer for sure fire results too. The RN-50 was designed to standard .50 BMG pressures. As is any other .50 BMG. With the safety margin figured in. Take your wonderful Barrett and keep shooting suspect ammo in it. Sooner or later it will fail. And rifle bolts do exit the receiver. BTW, how many of the vaunted AR15 bolts have sheared the bolt lugs and were launched backwards. View Quote Difference is those guns are designed to catastrophically fail in a manner that doesnt kill the operator. This gun, is not. |
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Quoted: Oh nonsense. Load up your favorite 30-06 full to the brim with Bullseye. And a 250 gr. bullet. Then sit behind the rifle and keep firing those super rounds. Good luck. Oh, add a magnum primer for sure fire results too. View Quote A Newton will eat two of those. Third one was too much though. |
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Quoted: Since most people can't get a 300rum barrel to live thru more than 800 rounds sub moa, and the fact that all steel has a stress/cycle life, and knowing this rifle spent most of its life shooting the original factory 180/3250fps ammo,(long ago detuned to 180/3200by Remington) it has been living on the edge its entire life, I see no reason to keep pushing it, especially since if I died tomorrow one of my kids would get it, and they would have no clue about action life expectancy...sure I could throw a new bolt in it, along with more smith labor, but seems like a waste of money considering the price of a tenacity action...which also eliminates sending the action stateside every time it needs a new barrel...at close to 200 bucks shipping round trip...Oh and most quality smiths are 8-12 months out for any work....swapping actions was an easy choice... View Quote The Tenacity is going to “wear out” the same way a built 700 would. |
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View Quote View All Quotes View All Quotes Threaded breech guns are a thing. However the thread forms are usually not 60 degree. Sometimes they are vertical in the holding side, stub acme form is also popular. If hot gas hits the thread or expands the cap you are in trouble. The military in EOD uses threaded breech 50 cal devices every day but not next to someone’s face meat. |
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As he admits, he did not know his ammunition. I recall an article about 40 years about a guy shooting surplus .303 British ammo in a machine gun. The stuff was incredibly old and there was a neck separation. Blew the receiver to bits along with an expensive gun. This was before the Hughes Amendment so while it was expensive, it was not as expensive as it would be now.
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Quoted: You miss the point, the ammo was the problem, yes. But the rifles design did nothing to mitigate danger to the shooter in the event of a failure. If shit explodes the rifle should also have a way to push the energy away from the shooter. View Quote View All Quotes View All Quotes Quoted: Quoted: 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. You miss the point, the ammo was the problem, yes. But the rifles design did nothing to mitigate danger to the shooter in the event of a failure. If shit explodes the rifle should also have a way to push the energy away from the shooter. Show me a .50 cal, or really any gun for that matter that has that kind of fail safe built into the design. |
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Quoted: This. This is a cheap homemade design by someone who doesnt know what he is doing, and doesnt understand safety. Most every modern gun takes into account the possibility of a Kaboom, and engineers it such that the Kaboom does kill the operator. This design though blows out the screw cap which shears the guide ears, all of which come back at the operators face. An AR Kaboom or Garand Kaboomz or almost any other gun Kaboom, would never fail in such a lethal manner. When he showed that cap hitting his glasses like that, I was like Holy Shit- he's lucky to be alive and still his vision from that alone. When he said, then it gets worse - I was like: what can get worse then that? Then he showed what happened with the Ears, that are just sitting there as part of the design. And how those basically turned into .22 bullets at .22 power, coming at his face. The dude took a .22 neck shot into his jugular. I"m still not sure how the F he lived thru that. If he didnt have support help there that knew what they were doing, no way would he have lived. Holy Shit Maybe I'll just sorta take .50 cal off the dream list, because that was some F'ing terrifying shit. View Quote this. I can't help but think even a relief vent cut upward and outward in that cap would have prevented the cap from going into his face. the pressure went through the primer and pressurized the space between the cap and the barrel. it makes me wonder if Mark even tested one to failure. |
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Quoted: 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. View Quote Bingo. Most bolt guns also have a gas relief hole in the bolt and receiver in the event of a ruptured case or blown prime to vent hot gas & pressure away from the shooters face. Multiple and redundant safety features. |
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20 minutes? Nope. Post the 5 second clip of the boom, then a link to the 20 minute monologue about it in another video.
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you guys do know sabots and muzzle brakes don't mix.. right? And there are warnings not to shoot slaps with the brake on. good chance on exit the sabot opens and becomes a blockage in the brake.
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Quoted: you guys do know sabots and muzzle brakes don't mix.. right? And there are warnings not to shoot slaps with the brake on. good chance on exit the sabot opens and becomes a blockage in the brake. View Quote I wouldn't think that would cause the failure we saw here. First, I doubt the sabot could hold back the pressure to the level that the breach grenades. The weak point in this case would be the end of the barrel/brake. I would have expected to see the muzzle brake grenade if this happened. However, I suspect this caution that you're referencing is more about loss in accuracy and possible damage to the brake, not catastrophic failure. It looks like this detonation happened in the chamber the moment the round was fired. |
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Quoted: this. I can't help but think even a relief vent cut upward and outward in that cap would have prevented the cap from going into his face. the pressure went through the primer and pressurized the space between the cap and the barrel. it makes me wonder if Mark even tested one to failure. View Quote View All Quotes View All Quotes Quoted: Quoted: This. This is a cheap homemade design by someone who doesnt know what he is doing, and doesnt understand safety. Most every modern gun takes into account the possibility of a Kaboom, and engineers it such that the Kaboom does kill the operator. This design though blows out the screw cap which shears the guide ears, all of which come back at the operators face. An AR Kaboom or Garand Kaboomz or almost any other gun Kaboom, would never fail in such a lethal manner. When he showed that cap hitting his glasses like that, I was like Holy Shit- he's lucky to be alive and still his vision from that alone. When he said, then it gets worse - I was like: what can get worse then that? Then he showed what happened with the Ears, that are just sitting there as part of the design. And how those basically turned into .22 bullets at .22 power, coming at his face. The dude took a .22 neck shot into his jugular. I"m still not sure how the F he lived thru that. If he didnt have support help there that knew what they were doing, no way would he have lived. Holy Shit Maybe I'll just sorta take .50 cal off the dream list, because that was some F'ing terrifying shit. this. I can't help but think even a relief vent cut upward and outward in that cap would have prevented the cap from going into his face. the pressure went through the primer and pressurized the space between the cap and the barrel. it makes me wonder if Mark even tested one to failure. It would appear others have been helpfully providing that data via "field events". Which has not been utilized in the engineer's creed of "DON'T DESIGN EXPLODY SHIT THAT KILLS YOUR END USERS" (they teach us this in school) |
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Quoted: Threaded breech guns are a thing. However the thread forms are usually not 60 degree. Sometimes they are vertical in the holding side, stub acme form is also popular. If hot gas hits the thread or expands the cap you are in trouble. The military in EOD uses threaded breech 50 cal devices every day but not next to someone’s face meat. View Quote View All Quotes View All Quotes Quoted: Threaded breech guns are a thing. However the thread forms are usually not 60 degree. Sometimes they are vertical in the holding side, stub acme form is also popular. If hot gas hits the thread or expands the cap you are in trouble. The military in EOD uses threaded breech 50 cal devices every day but not next to someone’s face meat. Buttress threads. |
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