50 Bmg Blow up....

stefan73

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    Yup! But they slide like butter. My AR50 is second smoothest “sliding” bolt I own. The cam over is a touch stiffer but otherwise it’s almost on par with my AI’s

    The BFG was sloppy. I also had to manually press the hammer down in the action so the bolt would clear it to close. I replaced the trigger/hammer before ever firing it as it was over 9 lbs from factory
    I slapped an Armalite AR50 muzzle break on the BFG-50, so much nicer.
     

    W54/XM-388

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    yup, my ar-50's bolt was like paper towel tube sized truck axel

    I had one of them AR-50 rifles.
    The thing damn near needed a trailer to pull it (joking).
    But it was the softest shooting .50BMG that I ever had.
    That tank brake will rattle a valley however.
     
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    hafejd30

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    I slapped an Armalite AR50 muzzle break on the BFG-50, so much nicer.
    I only fired the BFG a handful of times before I sold it. I thought the recoil wasn’t to bad for the weight of the rifle. Think it was 22 lbs with optic compared to 38 lbs with the Armalite. The Armalite obviously kicked way less and had a lot less muzzle jump but that was to be expected

    That AR 50 brake clears your sinuses that’s for sure
     
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    stefan73

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    That Armalite brake makes you feel like you are blowing out your fillings when you shoot! I noticed I get sinus issues after shooting it from the prone but it makes getting a good cheek weld and scope picture nicer since you aren't dotting your eye with every pull of the trigger (I am light so it shoves me around a little bit, I weighed 135lbs when I first bought my .50 BMG).
     

    armorpl8chikn

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    The RN50 to me is not a good design.

    Gotcha, thanks for clarifying. I have heard over twenty years of "fifty cal bad, could be used in a crime but hasn't been and my 06 is all I need" type crap, so I might be a little sensitive about it ;)

    There are better low (relative) budget fifties than the RN50, that is for sure.

    My 06 is all I need.....





    😁

    To be fair, my 06 is really bad ass. Some here have seen it, can testify.
     
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    Im2bent

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    My 06 is all I need.....





    😁

    To be fair, my 06 is really bad ass. Some here have seen it, can testify.
    Hey don't be bad mouthing the 06. Its the standard used for testing level 4 armor. I don't see no steenkin 50 bmg mentioned.
     
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    stefan73

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    Was being serious.
    My 06 is the only "big" rifle I have left.!
    You are missing out on life! I'm still trying to find a reasonable 12 pounder. But my wife is not as excited about the idea of a cannon as I am! I mean who else is going to fire off a cannon at 0630 for raising the flag? I'm not sure how my neighbors will feel 😁 and I am being serious.
     
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    hlee

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    You are missing out on life! I'm still trying to find a reasonable 12 pounder. But my wife is not as excited about the idea of a cannon as I am! I mean who else is going to fire off a cannon at 0630 for raising the flag? I'm not sure how my neighbors will feel 😁 and I am being serious.

    Cannon fire? Pretty sure that is @sirhrmechanic ‘s mating call. I suggest caution... 😂
     

    Im2bent

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    You are missing out on life! I'm still trying to find a reasonable 12 pounder. But my wife is not as excited about the idea of a cannon as I am! I mean who else is going to fire off a cannon at 0630 for raising the flag? I'm not sure how my neighbors will feel 😁 and I am being serious.
    Uhhhhh except how are you going to put powder in that thing even BP is near impossible to find.
     

    armorpl8chikn

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    You are missing out on life! I'm still trying to find a reasonable 12 pounder. But my wife is not as excited about the idea of a cannon as I am! I mean who else is going to fire off a cannon at 0630 for raising the flag? I'm not sure how my neighbors will feel 😁 and I am being serious.
    Cervical spine fusion that didn't fuse, a broken screw, more vertebrae that are degenerating. Im not even supposed to shoot my 06.

    Not happy about my shooting days being behind me, but there it is.
    That was what I was referencing.
    I CAN'T shoot a 50. Wouldnt dream of it.
    Last time I shot my 11lb precision AR was about 10 rounds total. Had a spinal headache for days.

    I just live vicariously through you fellers.
     

    6.5SH

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    Cervical spine fusion that didn't fuse, a broken screw, more vertebrae that are degenerating. Im not even supposed to shoot my 06.

    Not happy about my shooting days being behind me, but there it is.
    That was what I was referencing.
    I CAN'T shoot a 50. Wouldnt dream of it.
    Last time I shot my 11lb precision AR was about 10 rounds total. Had a spinal headache for days.

    I just live vicariously through you fellers.
    That sucks. Do what you can, even lobbing .22's at 3-500 yards can be a hell of a challenge (and fun).
     

    mcameron

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    Cervical spine fusion that didn't fuse, a broken screw, more vertebrae that are degenerating. Im not even supposed to shoot my 06.

    Not happy about my shooting days being behind me, but there it is.
    That was what I was referencing.
    I CAN'T shoot a 50. Wouldnt dream of it.
    Last time I shot my 11lb precision AR was about 10 rounds total. Had a spinal headache for days.

    I just live vicariously through you fellers.
    honestly man, you arent missing much.....picture .300 win mag recoil with a lot more muzzle blast.....


    if you want the .50bmg experience, wait until you have a sinus infection, take a braked .300 win mag to the range, shoot under an awning, and throw $20 bills down range while shooting.....pretty much the same thing.
     

    stefan73

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    Cervical spine fusion that didn't fuse, a broken screw, more vertebrae that are degenerating. Im not even supposed to shoot my 06.

    Not happy about my shooting days being behind me, but there it is.
    That was what I was referencing.
    I CAN'T shoot a 50. Wouldnt dream of it.
    Last time I shot my 11lb precision AR was about 10 rounds total. Had a spinal headache for days.

    I just live vicariously through you fellers.
    Disk replacement, degenerative, arthritic and some bulging disks, some more collapsing basically C-S, broke three vertebrae. I can empathize.
     

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    stefan73

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    honestly man, you arent missing much.....picture .300 win mag recoil with a lot more muzzle blast.....


    if you want the .50bmg experience, wait until you have a sinus infection, take a braked .300 win mag to the range, shoot under an awning, and throw $20 bills down range while shooting.....pretty much the same thing.
    Heathen😁😁
     
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    E. Bryant

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    Uhhhhh except how are you going to put powder in that thing even BP is near impossible to find.

    Er, what?



    It's been about the only type of powder I've seen consistently in-stock at Midway and other "big" stores throughout the last several months. Admittedly, I'm not sure if particular granulation sizes have been harder to find.
     

    W54/XM-388

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    Tripod mounts are all the rage these days it seems in PRS and others.
    It's not a huge stretch to go back to mounted guns from there really.

    So you just design a new tripod that has ground anchor bolts (like one of those .22 cal nail gun drivers) and can fully absorb the recoil so you just mount up your rifle, get behind it, pull the trigger and let the tripod take all the punishment.

    Then you can shoot your .50BMG or any big stuff just fine and could even take off the muzzle device if needed.
     
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    stefan73

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    Er, what?



    It's been about the only type of powder I've seen consistently in-stock at Midway and other "big" stores throughout the last several months. Admittedly, I'm not sure if particular granulation sizes have been harder to find.
    Near me (like 10 miles). https://www.jackspowderkeg.com/
     

    Baron23

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    Cervical spine fusion that didn't fuse, a broken screw, more vertebrae that are degenerating. Im not even supposed to shoot my 06.

    Not happy about my shooting days being behind me, but there it is.
    That was what I was referencing.
    I CAN'T shoot a 50. Wouldnt dream of it.
    Last time I shot my 11lb precision AR was about 10 rounds total. Had a spinal headache for days.

    I just live vicariously through you fellers.
    Wow, so sorry to hear all of this. I have bone on bone in L4/5, had surgery 13 years ago for bad herniated disk and not the rest of the disk is just gone, and the next step they are talking about is fusion.

    I am trying to avoid fusion as long as I can due to stories like yours. If it works, great. If you have problems, too bad as its the end of the road.

    Best of luck to you, my friend. I hope that you can find a way to shoot with your current condition. Precision rim fire from a bench, maybe?
     

    armorpl8chikn

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    Wow, so sorry to hear all of this. I have bone on bone in L4/5, had surgery 13 years ago for bad herniated disk and not the rest of the disk is just gone, and the next step they are talking about is fusion.

    I am trying to avoid fusion as long as I can due to stories like yours. If it works, great. If you have problems, too bad as its the end of the road.

    Best of luck to you, my friend. I hope that you can find a way to shoot with your current condition. Precision rim fire from a bench, maybe?

    I still shoot. I have a couple specialty pistols for hunting.
    I moved where the heat keeps me more limber too.

    I had severe stenosis. I had no choice on surgery. I was a bad fall or mild fender bender from being paralyzed. I'm WAYyy better than I was. I dont complain, just miss what I used to do. I can have surgery again, it was offered, but....no guarantee ill be any better than I am now.
    I know my limits, dont always follow them and when I don’t , I know the cost.
    Its all much better than it could be.
     

    stefan73

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    I still shoot. I have a couple specialty pistols for hunting.
    I moved where the heat keeps me more limber too.

    I had severe stenosis. I had no choice on surgery. I was a bad fall or mild fender bender from being paralyzed. I'm WAYyy better than I was. I dont complain, just miss what I used to do. I can have surgery again, it was offered, but....no guarantee ill be any better than I am now.
    I know my limits, dont always follow them and when I don’t , I know the cost.
    Its all much better than it could be.
    Same thing here. I had issues with loss of sensation in the extremities. Talking with my primary care provider I told her about accidently spilling water from the kettle on my hand while making tea and not realizing it (I think something had come on TV that distracted me while I was poring the boiling water from the kettle and I just didn't realize that I was poring it on my hand at the moment, a few days later my wife was wondering why my hand was all crusty/scabbed up) or when I bounced a big hammer off a bearing and hit my hand and it didn't bother me (watched it swell up like a balloon), or when I would cut myself working on the truck or tractor and not realize it till my daughter would tell me that I am bleeding (after I ruined another pair of jeans :mad:). So I had an MRI done, was sent to a neurosurgeon and told I needed surgery in the next 30 days. So Dec I had it done, made for a great Christmas:cautious:
    My wife would yell at me for moving bags of feed after the surgery (those bags weren't going to move themselves). Anyways, a little bit of the sensation has returned but not much. Some things I feel and some I don't.

    Like you, could have been worse. I am glad that I don't have to rock a wheelchair.

    A couple of guys I know had the fusion, they wished they had done it earlier. Sucks to hear that yours isn't going as well.
     

    Baron23

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    First shot on a 50BMG since he almost died, take a wild guess what fuckin brand of rifle he shoots 🤣

    I kind of like this fella's energy and positivity....but insofar as he shot ANOTHER FUCKING SERBU gun....I have to seriously question his intelligence and most certainly question his judgement. Not sure I would want to be on a range with someone so apparently dense to extreme lessons of life.

    WTF dude....find almost ANY other BMG other than something made by Serbu.

    Wow....just wow.
     

    Maggot

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    Cervical spine fusion that didn't fuse, a broken screw, more vertebrae that are degenerating. Im not even supposed to shoot my 06.

    Not happy about my shooting days being behind me, but there it is.
    That was what I was referencing.
    I CAN'T shoot a 50. Wouldnt dream of it.
    Last time I shot my 11lb precision AR was about 10 rounds total. Had a spinal headache for days.

    I just live vicariously through you fellers.
    Handguns. You can make plenty of noise and tear up some stuff with a good handgun.
     
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    BoltRunner

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    Ok a Serbu rifle exploded like a fuckin pipe bomb an tore through his body like Navy Seals in a 3rd World County... Guy barely survived and spent the past 3 months going through surgeries and rehab... Finally decides it's time to get back on that 50BMG horse after much thought... Hmmmm what rifle, what rifle to choose...??? So many choices... I know a fuckin Serbu...!!! 🙈💥💥💥☠️☠️☠️⚰️⚰️⚰️
     

    1500varmint

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    Ok a Serbu rifle exploded like a fuckin pipe bomb an tore through his body like Navy Seals in a 3rd World County... Guy barely survived and spent the past 3 months going through surgeries and rehab... Finally decides it's time to get back on that 50BMG horse after much thought... Hmmmm what rifle, what rifle to choose...??? So many choices... I know a fuckin Serbu...!!! 🙈💥💥💥☠️☠️☠️⚰️⚰️⚰️

    This is where I landed as well.

    He seems like a nice guy, so i'm glad he's getting back into the swing of things...but a SERBU?
     
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    CMP70306

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    So he will shoot another POS Serbu, you know the company that hires potheads to build their guns, but has to hide behind a truck to shoot a double rifle in 700 Nitro because he isn’t sure its safe? If he isn’t sure is safe why the fuck did he buy a 1968 10 gauge converted to .700 Nitro?

     

    Gtscotty

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    Hi,

    This may get long, so I apologize in advance if it does....

    Here is my stance on this situation:

    1. No firearm, no matter how shitty of a design can have a catastrophic failure such as the KB one without AMMO.
    So the shooter is accountable for that but only that portion of the event in its' entirety. I do not believe the shooter is accountable for anything after pulling the trigger.

    2. Once the KB guy essentially started the entire chain of events it is the FIREARMS job to stop the chain of events from being so catastrophic.

    In this exact rifle design that starts with something as simple as 45 degree (away from shooter) gas vent holes in that screw cap.

    Simply done via 2 drills with a 1/4 inch bit.

    That way even during complete case head rupture the gases would not blow the threaded cap off in that such a manner.

    As soon as the gas "escaped" the "boltface" area in this screw cap design it put too much force across a larger section in which ripped the screw cap off. No amount of threads in that alloy was going to hold that screw cap on.

    In this exact rifle design we can get deeper into the science of it in regards to that screw caps actual weight.
    For example IF that screw cap was twice its weight (not size, but alloy weight) then the same amount of pressure would not be able to blow it with same speed and force.
    In turn slowing the entire series of events down in regards to how deep the KB throat was cut??
    In turn slowing the entire series of events down to the 2 rabbit ears could have helped better since the cap would not have been going with such speed??

    Some firearms forensic examiner in Italy threw out some formulas in which the objects would have been moving at a 1/4 of the speed so in theory KB cuts would be a 1/4 of the depth they are right now.

    Same examiner has offered to examine this rifle free of charge and anyone want to wager IF he gets that opportunity??

    Sincerely,
    Theis

    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.

    ^ In my opinion, this is pretty easily the most credible theory out of any I've heard tossed around. Doesn't require any magic or overlap of low probability events, just a bad design and a case head separation (possibly even helped along by a special loose chamber, although that's not necessary).

    Once the gas escapes the case into the bolt (cap?) head area, it starts acting on a much larger cross section, and as long as the volumetric expansion doesn't cause the max pressure to drop much, total force on the cap skyrockets.

    I don't even know that I buy that the ammo was overpressure, it doesn't seem like it would need to be. Maybe a case separation plus a slightly loose cap, or slightly out of tolerance threads could do it. Maybe when the leak pressurizes the chamber, the pressure is able to act radially on part of the plug to expand it a little, further reducing thread shear area. Or maybe nothing at all other than a case head separation and the resultant increased force on the plug is required to make things pop, and this is how all RN50 case head separations end.... Any way you cut it, it's a pretty bad design.
     
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    seanh

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    Dude already came out and said the ammunition was "Tampered with"… likely a detonation, wrong powder, over charged.
     
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    Gtscotty

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    Dude already came out and said the ammunition was "Tampered with"… likely a detonation, wrong powder, over charged.
    I didn't click on all of the videos and links in the thread, did someone pressure test the ammo KB was using?
     

    seanh

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    I didn't get that information in this thread I got up by doing a little research.

    Whether or not those rounds will pressure tested, don't know, Haven't looked. Even if QC calls for pressure testing, accidents happen.

    Personally I'd like to see the action polished, etched ( Those ears that sheared) and look at it under the appropriate lighting and microscope to check out the grain structure... See if it's a materials failure, machining failure or user error
     

    E. Bryant

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    I didn't get that information in this thread I got up by doing a little research.

    Whether or not those rounds will pressure tested, don't know, Haven't looked. Even if QC calls for pressure testing, accidents happen.

    Personally I'd like to see the action polished, etched ( Those ears that sheared) and look at it under the appropriate lighting and microscope to check out the grain structure... See if it's a materials failure, machining failure or user error

    The video where Serbu receives his pipe bomb for inspection and analysis (posted somewhere previously in this dumpster fire) shows Mark removing the cartridge case (minus its head) with one of those GI extraction tools. It slid right out with a tap on a cleaning rod. Not what I'd expect for a massive overpressure event that would be suggested by defective or sabotaged ammo.

    You can do whatever analysis you wish on those ears, but it doesn't matter since they are not designed to retain the cap in the event of thread failure (and if that was the intent, then the required analysis needs to be applied to whatever putty-like material is sitting between the designer's ears). If the threads fail, those lugs will be exposed to, oh, maybe 40,000 lbs of force. My bet is that the geometry of the lugs and cap results in a point load near the tip of each lug in this situation, and the resulting force attempts to simultaneously bend them rearward and outward. The ol' "eyeball FEA" suggests they're gonna break, but sure, poke and prod away at the design and material if one wishes.
     

    Baron23

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    I do wish Kentucky Ballistics the best of luck....I admire his energy, positivity, and general outlook. I'm glad that he seems to have recovered from this catastrophe and is healthy. Seems like he'd be a great guy to have a beer with.

    But that man needs to seriously rethink what he's willing to shoot, IMO.
     

    KZP

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    Something I've been wondering, would excessive head space cause the case to separate, allowing increasing pressure to failure? If so, how much would it take assuming this is within standard 50 bmg pressures?

    What if small debris got lodged between the receiver and threaded cap causing incorrect headspace. Serious doubts about those metal ears providing a perfect safety check for the cap being closed correctly. A person could screw it down tight thinking it's on, snap it shut, but there is actually a small gap because something like a small brass shaving or sand got in-between the cap face and receiver.
     

    brianf

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    Something I've been wondering, would excessive head space cause the case to separate, allowing increasing pressure to failure? If so, how much would it take assuming this is within standard 50 bmg pressures?

    What if small debris got lodged between the receiver and threaded cap causing incorrect headspace. Serious doubts about those metal ears providing a perfect safety check for the cap being closed correctly. A person could screw it down tight thinking it's on, snap it shut, but there is actually a small gap because something like a small brass shaving or sand got in-between the cap face and receiver.
    …exactly…

    that’s why you dont design a rifle like a plumber
     

    E. Bryant

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    Something I've been wondering, would excessive head space cause the case to separate, allowing increasing pressure to failure? If so, how much would it take assuming this is within standard 50 bmg pressures?

    What if small debris got lodged between the receiver and threaded cap causing incorrect headspace. Serious doubts about those metal ears providing a perfect safety check for the cap being closed correctly. A person could screw it down tight thinking it's on, snap it shut, but there is actually a small gap because something like a small brass shaving or sand got in-between the cap face and receiver.

    Generally speaking, excessive headspace won't cause a case head separation on the first shot. Instead, what tends to happen is that the brass stretches, someone mashes it back to minimum spec when they resize, and then rinse/repeat until the brass can't take the abuse after some number of reloads. Now, I'm not ready to put my face in the direct path of demonstrating this on a 50BMG pipe bomb, but it's pretty stunning what smaller calibers can tolerate in terms of headspace.