Comments

1. On April 30, 2021 at 9:39 am, Paul B said:

   I know a guy that has one of those. Not sure he ever shot it. Know now I will never own one.

   That is one lucky dude.

2. On April 30, 2021 at 12:01 pm, Andrew said:

   From comments elsewhere, guy tried to shoot a round of “SLAP”, which apparently isn’t meant for use with a muzzle brake equipped blaster, they’re meant for the M2.

3. On April 30, 2021 at 2:04 pm, Georgiaboy61 said:

   “SLAP” = sabot light-armor penetrating…

   It’s a big no-no to use that in any weapon with a muzzle device, unless that device was expressly cleared as safe for use with sub-caliber sabot ammunition.

   The penetrator portion of the munition is sub-caliber, meaning smaller than the bore of the rifle or cannon from which it is being fired. It is also often lighter and more-highly streamlined, to allow it to be driven to very high muzzle velocity. The sabot or “shoe” (“sabot”means shoe) portions – which are typically light in weight – of the projectile are just there to provide the necessary thickness to bring the sub-caliber projectile up to bore-size. The propellant charge drives the full-bore projectile, and when it clears the muzzle, the shoes/sabots peel away, allowing the penetrator/sub-caliber munition to fly to the target unimpeded.

   The British first-invented APDS tank ammunition for their famous 17-pounder gun during the Second World War, for use in the M4 Sherman “Firefly” series and other AFVs equipped with the gun (Archer, Achilles, etc.) as well as conventional 17-lb. AT artillery pieces. The gun on the Sherman Firefly had a muzzle brake, but of unconventional design.

   Of course, modern tanks which employ sabot-type ammo are now quite common, for example, the U.S. M1 Abrams series, whose Rheinmetall 120mm smooth-bore gun does not have a muzzle brake.

   Like Paul B. said, that cat was one lucky dude. The outcome could have been much worse than it was…. good thing it wasn’t Raufoss Mk. 11 ammo!

4. On April 30, 2021 at 6:18 pm, Geoff said:

   The video is a black screen and the latest Firefox does not have the “Restart with Addons disabled” now. Version 88.0 64 bit.

5. On April 30, 2021 at 6:36 pm, Geoff said:

   Apparently all videos of the BOOM have been removed and the Kentucky Ballistics Channel is nonexistent now. I can’t find anything but a very short slomo clip.

6. On April 30, 2021 at 6:43 pm, Geoff said:

   Well, it seems the new version of Firefox is the problem. I guess I’ll have to downgrade to teh previous version. MS EDGE works fine

7. On May 1, 2021 at 9:31 am, Ned said:

   I cringed in a previous Kentucky Ballistics video where he was shooting a SLAP round out of the same gun at an “atlas stone” with the same muzzle brake. On page 15 at this link are some good cross section views of SLAP rounds and a photo of the sabot coming off in flight. A long four chamber brake like the one on this Serbu gives an even greater chance for a sabot strike than a shorter brake. Scary stuff.

   https://ndiastorage.blob.core.usgovcloudapi.net/ndia/2011/smallarms/WednesdayAmmo12322Howard.pdf

8. On May 1, 2021 at 10:19 am, ragman said:

   I watched a couple of this guys vids and seems to me he likes to “torture test” firearms. Thank God he wasn’t killed! That rifle looked like something I would never shoot.

9. On May 3, 2021 at 10:32 am, Silence DoGood said:

   This explosion could NOT have had anything to do with the sabot of the final round fired fouling in the muzzle brake.

   The normal pattern for a pressure curve is for pressure to increase for the first inch or so of bullet travel, by which time chamber pressure will have reached its maximum. Then it decreases progressively as the bullet travels further down the barrel. We know to a certainty that the bore was clear prior to the final shot because the projectile from the previously fired round was lodged in the fire plug. So we also know to a certainty there was no mechanical obstruction to prevent that final shot’s pressure curve being perfectly normal.

   Lilja has a .50 BMG pressure chart (https://bit.ly/2RizVk3) showing that bore pressure will have fallen to less than 8000 psi by the time the bullet reaches the muzzle of a 36-inch barrel. Admittedly that’s not for a SLAP round, but it’s a hell of a long way from 8000 psi to >85,000, which is what Mark Serbu stated would have been necessary for the threads on the breech plug to fail.

   Which is not to say that there couldn’t have been a problem with the sabot fouling in the muzzle brake, but since we know that the bore was clear before that shot, any problems caused by the sabot would not have arisen until the following shot. The shot that exploded should have been GTG from any potential barrel obstruction.

   I’m doubtful of Scott’s “overcharge” theory because the SLAP round’s charge is 275 grains of WC856 (data here: https://bit.ly/3eOfxiL). The .50 BMG is admittedly a YUGE cartridge case (292.8-gr of H2O) but when loaded with 275 grains of powder, there just isn’t a lot of space remaining for an overcharge.

   The performance of the first two SLAP rounds was inconsistent enough that it might have been taken for a warning, but just two rounds is a very small data set to pick up on any ‘trend.’ And it’s easier for me to “armchair quarterback” this and make the more logical call than it was for the man behind the trigger. Because not only was their trajectory wildly different, so was their recoil. Notice how much less Scott’s right shoulder recoils after the second SLAP shot, the one that produced the giant fireball.

   That’s why I don’t think it was overcharged, I think it was undercharged, resulting in Secondary Explosion Effect. Because SEE causes the powder to explode, not conflagrate, and gunpowder that well and truly explodes generates a YUGE pressure spike in excess of your garden variety double-charge, so severe that it typically also causes catastrophic structural failure of the firearm.

   Maybe all three of the SLAP rounds were undercharged but it didn’t reach the breaking point until the the rifle got warmed up by the two SLAP rounds followed by the API round (I should note that both PO Ackley and Norma’s Nils Kvale tried to reproduce SEE under laboratory conditions but neither could do it predictably).

   But considering what is known to have occurred before that final shot, it’s not possible that the sabot was the cause of this. The physics just isn’t there.

10. On May 3, 2021 at 5:18 pm, The Wretched Dog said:

    I appreciate Silence DoGood’s explanation. My conclusion – upon watching the video and seeing the energy released where the barrel flipping end-over-end – was that the cartridge detonated in the chamber: effectively SG’s Secondary Explosion Effect. I just don’t see the muzzle brake problem of saboted rounds causing such overpressure.

    If I owned any slap rounds, or any other milsurp of dubious provenance, I would be inclined to pull the projectile so as to weigh and examine the powder.

    TWD

11. On May 3, 2021 at 8:10 pm, Herschel Smith said:

    @Silence,

    You’re not thinking about this as a physicist. The issue isn’t the pressure at the end of the muzzle and what a muzzle device does to that, but rather, what effect that delta-P between having and not having a muzzle device does to pressure at the other end of the bore. What change to the profile occurs.

    This is a system, and you’re looking at it as a discrete problem at the end of the muzzle.

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