Kentucky Ballistics tests second RN 50

[davidjoe]

Scott uploaded today a new video that tests to destruction an RN 50 provided by Serbu. It’s definitely worth watching as this accident in 2021 that almost killed him left a lot of questions and speculation.

Scott fires his tests from behind a cinder block wall, and picks up with the remaining SLAP rounds from the lot he shot in April, 2021. They are definitely over-pressured and almost impossible for him to extract, after the cap is pried open with a wrench and two people. But, Scott still doesn’t go into the source of SLAP rounds, and apparently that plastic bag of them is now depleted, without disassembling any of the ammo to find out what the cause was.

He does state it was likely “counterfeit” SLAP ammo, but that could mean there is more of it loaded in similar manner widely dispersed, and destined to be problematic, though it took a “special” overloaded round to replicate the explosion. But Scott did prove that the one round that exploded his rifle was just one of many high pressured, that were not fired that day. I’m wondering if guys familiar with buying and using SLAP rounds have been wary of over pressure or identified a faulty source.

 

[SKWERLZ]

Those remaining slap rounds were obviously well beyond safe pressure.
For what they charge for them I could totally see someone shady making fakes.

 

[Catfur]

Where would you get and machine the tungsten to make profitable fakes? I suppose you could use steel, but given steel weighs less than half what tungsten weighs per volume, you'd really have to screw up the powder to make them go boom.

I strongly suspect the powder in those rounds went bad. Maybe it was a bad batch of powder that should have been recalled. Maybe they were stored someplace really friggin hot for a long ass time and went south.

I can easily imagine surplus rounds sitting in a warehouse in the gulf after Iraq War I and being baked to the high heavens before coming back to the US of A to be sold for big $. Or something like a cheap, un air-conditioned storage unit in Tuscon or Bakersfield for 20 years before being re-discovered and sold off.

 

[ebb]

Davidjoe i am not up to speed on what is going on here but do remember the rifle blowing up and the shooter getting hurt bad. Have they decided that it was the ammo and not the rifle?

 

[davidjoe]

Davidjoe i am not up to speed on what is going on here but do remember the rifle blowing up and the shooter getting hurt bad. Have they decided that it was the ammo and not the rifle?

I think both Scott and Mark Serbu clearly attribute the failure to over pressure ammo.

So this time around, Scott set out to retest his accident’s circumstances behind two barriers, (a wall and his truck) using a tigger string, and put about 13 rounds through a gun he said he received from Mark Serbu, who had sent it to Scott expecting a typical KB test (torture) and video.

Scott clearly over stresses the barrel and cap threads multiple times with the high pressure SLAP ammo. I would infer that each instance of prying metal apart means slight metal movement had occurred during the shot, but not so much the breach won’t close.

Ultimately, the purpose loaded “proof” round designed to cause failure, at about three times max operating pressure was used, and it created an explosive failure where the barrel threads stripped like the original accident, and the cap blew off, which Scott says he could not find after looking for 45 minutes. (I saw large hole in the ballistic “head” but have to assume he did check there as well, for it). Edit, it appears on slow motion to have ricocheted off the wall). The cap forced its way between the lugs, expanding the plates violently to failure. Though the lugs remained attached this time, the cap was blown off so forcefully it could not be found, and something put that large hole in the “head”.

This test gun gave Scott a lot of warning that his threads were overstressed. That’s what I’d hope for as a user. The original gun did not, though, as far as we know. While this gun, appearing to be new when delivered, gave out on a round designed to destroy it and “warned” Scott that it was accumulating damage, I have to wonder if the well used guns out there (there’s only about 1,200 if I recall) would behave more like the test gun or the original gun with bad SLAP rounds. (It’s also concerning that a user conceivably could have just put this gun back in the closet with the SLAP round abuse or resold it in a weakened condition that’s not really observable).

Either way, imo it’s not ideal to see the cap, which serves as the “bolt” on this gun, project rearward so forcefully. I don’t have one of these but I do have 50’s.

 

[SKWERLZ]

I think both Scott and Mark Serbu clearly attribute the failure to over pressure ammo.

So this time around, Scott set out to retest his accident’s circumstances behind two barriers, (a wall and his truck) using a tigger string, and put about 13 rounds through a gun he said he received from Mark Serbu, who had sent it to Scott expecting a typical KB test (torture) and video.

Scott clearly over stresses the barrel and cap threads multiple times with the high pressure SLAP ammo. I would infer that each instance of prying metal apart means slight metal movement had occurred during the shot, but not so much the breach won’t close.

Ultimately, the purpose loaded “proof” round designed to cause failure, at about three times max operating pressure was used, and it created an explosive failure where the barrel threads stripped like the original accident, and the cap blew off, which Scott says he could not find after looking for 45 minutes. (I saw large hole in the ballistic “head” but have to assume he did check there as well, for it). The cap forced its way between the lugs, expanding the plates violently to failure. Though the lugs remained attached this time, the cap was blown off so forcefully it could not be found, and something put that large hole in the “head”.

This test gun gave Scott a lot of warning that his threads were overstressed. That’s what I’d hope for as a user. The original gun did not, though, as far as we know. While this gun, appearing to be new when delivered, gave out on a round designed to destroy it and “warned” Scott that it was accumulating damage, I have to wonder if the well used guns out there (there’s only about 1,200 if I recall) would behave more like the test gun or the original gun with bad SLAP rounds. (It’s also concerning that user conceivably could have just put this gun back in the closet with the SLAP round abuse or resold it in a weakened condition that’s not really observable).

Either way, imo it’s not ideal to see the cap, which serves as the “bolt” on this gun, project rearward so forcefully. I don’t have one of these but I do have 50’s.

I personally don’t fault the rifle but it’s obviously nothing to get into the sporty pressures with.


He had bolt/cap stamping immediately
That’s some serious pressure.

 

[Tokay444]

Mark’s rifle is going to kill someone, unless all owners start shooting them properly. From behind cinder block walls.

 

[LiveFire]

I have not watched the new video yet but I was under the impression it was shooting the slap round through a muzzle break that caused this. I watched an explanation from forgotten weapons I think it was. Something about the sabots getting hung up in the break acting as an obstruction. Perhaps I misunderstood the explanation.

 

[C_Ackley]

Case head stamped itself into the cap, primer flat as a pancake, primer pocket expanded, case head bulging, near impossible extraction, how far overpressure do you believe he was?
I'd guess twice SAAMI, so 120,000psi. Surprised the gun held up to all 12 that he had.

 

[LiveFire]

Just watched the new video. I couldn't help but feel every time he threaded that cap on he was completing a bomb.

 

[ebb]

Yea i don't see anyone here shooting unknown ammo sourced from a plastic bag bought who knows where. With that said how is the rifle to blame? the Boss won't let reloaded ammo be sold in the classifieds and yet we are seeing just that happen here and are still blaming the rifle?` I 50BMG ammo sold at the gun show and wonder who in the world would shoot that stuff, but many spend there money on a 50 and will not spend what it takes to buy the very expensive reloading equipment and components. I looked at 50s many years ago and decided 338 was as far as I could afford.

 

[whatsupdoc]

Project Eldest Son - Wikipedia

en.wikipedia.org

Ammunition - Ammunition Sabotage

 

[SKWERLZ]

Case head stamped itself into the cap, primer flat as a pancake, primer pocket expanded, case head bulging, near impossible extraction, how far overpressure do you believe he was?
I'd guess twice SAAMI, so 120,000psi. Surprised the gun held up to all 12 that he had.

I think I Read stamping generally starts at 90K
I’m trying to find that information.

 

[darkangel_r2]

A little more destruction testing and redesign to make the overpressure failure mode a little less harmful to the shooter is a good idea. But I suppose its kind of silly to expect a 50 bmg overpressure failure to be safe. I just don't like that stuff comes back at you when it fails.

The gun will obviously handle correctly loaded ammo safely and flawlessly. Just wished if it does break it broke differently.

 

[Rodney]

I think the rifle held up remarkably well and proved it’s strength 12 times with the remaining S.L.A.P. rounds. Scott was checking for bore obstruction each time. Can’t see a Barrett firing all 12 rounds. Really would like to have seen one of the rounds dissected though. I’m leaning towards improper ammo storage being the culprit, but I guess we’ll never know. He says the “proof” round was loaded to 190,000 psi. The video shows just how lucky he is to be alive. Great teaching moment there for anyone shooting military surplus ammo.

 

[dantiff2]

I'd have a hard time shooting that particular rifle just because of the design (breech cap) after seeing what happened to Scott of KB. There were no warning signs with his original rifle like there were repeatedly when trying to replicate the boom. On the other hand. Who's to say a bolt action 50 wouldn't shear the lugs and send the bolt body rearward into the shooters face?
Dan

 

[C_Ackley]

There were no warning signs with his original rifle like there were repeatedly when trying to replicate the boom.

When talking about 3-4x overpressure, I don't see how you can reasonably expect there to be a warning sign before it goes kaboom. I was skeptical the first time, but having seen the genuinely insane pressure signs and the gun eat 12 of them, I'm pretty confident you have to be trying to injure yourself to worry.
Bottom line is don't use mystery ammo, that stuff may have been made to sabotage enemy munitions.

 

[dantiff2]

When talking about 3-4x overpressure, I don't see how you can reasonably expect there to be a warning sign before it goes kaboom. I was skeptical the first time, but having seen the genuinely insane pressure signs and the gun eat 12 of them, I'm pretty confident you have to be trying to injure yourself to worry.
Bottom line is don't use mystery ammo, that stuff may have been made to sabotage enemy munitions.

In this case, the weapon clearly took the abuse of the 11 remaining original 12 rounds. Why didn't the first gun? Maybe there was fatigue on the breach threads from the round count that led up to the kaboom? we'll never know. I also agree 100% on trusted ammo only but I have experience with 50bmg ammo not all being equal. I shot a bunch of USA brand, commercially produced Talon brand 50 bmg ammo through my ALS (Advanced Long Range) upper and every now and then I would get a round with extreme stiff bolt lift. Even had one break my extractor with trying to lift bolt and tap on case with cleaning rod and had to have that replaced by Darin from ALS. 50 ammo is all over the place as far as what's out there.
Dan

 

[C_Ackley]

In this case, the weapon clearly took the abuse of the 11 remaining original 12 rounds. Why didn't the first gun?

Roulette, not every round was substantially over-pressure and all it takes is one so grossly over to blow up a firearm. I think Scott just found that round early that day.

 

[Rodney]

Roulette, not every round was substantially over-pressure and all it takes is one so grossly over to blow up a firearm. I think Scott just found that round early that day.

That’s why I think it was improperly stored ammo. The pressures were all over the place with some seeming normal almost, but some were WAY over pressure for sure.