AR-15 Kaboom — “The Worst … I Have Ever Seen”
This shocking photo of destroyed AR-15 bits and pieces was posted on Facebook by William Walter, a firearms instructor. William said this was “The worst AR-15 blow-up I have ever seen. Has anyone else seen one this bad?” It is indeed catastrophic. Seeing the above image, our friend Grant Ubl wrote: “that is most definitely THE most FUBAR’d AR15 that I have ever seen”.
Luckily the shooter sustained only minor injuries — nothing worse than a broken finger tip. But his AR-15 is certainly toast. The lower was polymer. Note the past tense. According to Walter: “It was a polymer lower and polymer magazine. Pieces of both were distributed up to 25 feet from the bench he was firing from.”
The cause of the Kaboom is somewhat mysterious. The Kaboom occurred on the 4th round fired — the first three went OK, and there is NO evidence of a squib load (i.e. no bulge in barrel). This was definitely NOT a .300 BLK round in a .223 Rem Chamber. William Walter suspects that pistol powder may be involved, but that has not been confirmed.
First thing I suspected was bore obstruction, but there wasn’t any sign of it. The case head literally atomized…you can see the brass residue on the parts. The bolt was split in two also. This was number four fired during load testing. The previous three were fine…no high pressure signs on the primer. — William Walter
One Facebook poster noted: “We had one similar here in PA about 14 years ago. The guy used Winchester 231 instead of Winchester 748 and ended up with a pile of parts very similar looking. The rifle went Kaboom on his first sighter in offhand and no one was injured surprisingly. The carrier looked like someone cut it down the middle with a torch very similarly to this picture. It also cut the bottom of the carrier and all three pieces look like a peeled banana.”
Walter stated that here: “[The shooter] had fired four rounds of the same load. He was shooting Win 748…24 grains with a 77 Sierra. I will reserve my theory until after we discuss as to not steer the conversation.
On reading that, Dennis Santiago posted: “Did you mean WW 748? That’s on the fast side powder for a .223 meant for lighter bullets. 24 grains with a long bullet like a Sierra 77 would be way too much.”
Walter noted that there was a possibility of some pistol powder getting into the catridge that detonated: “[The shooter] said he does load pistol and this was first time loading rifle. He said he used his 650 powder measure, but also a funnel and trickler.” Considering that, one poster suggested that maybe pistol powder was still left in the bottom of the powder measure.
It will be interesting to determine what exactly happened here. The remaining rounds from the same loading session will be pulled down and analyzed. A discussion of this incident appears on the Precision Shooting Journal Facebook Page.
Hi,
I remember the May 10th kaboom exp(l)osed on http://bulletin.accurateshooter.com/2014/05/ammo-failure-detonation-in-3-gun-match-watch-and-wince which is probably the same reason as the one today.
At the time I gave Paul my answer to explaine the kaboom, but it was not published.
Please find the PDF in english on : http://www.simplyright.ch/accurateshooter/pdf/Kaboom_20140510_ENGLISH.pdf
Best regards from Switzerland !
Florian
At my second ever NRA High Power match, the shooter next to me, on the right end of the firing line, had his M1 rifle explod on the first shot. It was in Fairbault, MN in the early 1990’s time frame. Turns out he had made up his first ever reloads and he had WW231 in those 30/06 cases. The gun exploded forward and to the right of the shooter, as designed. Had he been in the middle of the line, we could have had more people injured than just the shooter.
Ya the only way your going to do that is a full case of pistol powder shot by someone that shouldnt been reloading in the first place.
I have had one go kaboom also, but we found the big was machined wrong and allowed the firing pin to strike the primer out of battery before the bolt lugs were engaged. This was an A-10 and 243 loaded normal. The magazine opened up and upper was damaged the brass case was in pieces. Now I inspect all bcg to insure the firing pin does not follow the bolt as the bolt I extended to the open position. The defective bcg allowed the firing pin to follow and fall out of sight verses being held by a shoulder in the carrier.
Obviously a high pressure event. My guess is two bullets loaded in a single round in combination with a material problem. I have seen many over pressure failures in my 35+ years of working with AR-15’s I have never before seen a hoop stress failure of a barrel extension. Normally the bolt lugs sheer leaving the extension intact. There may be evidence of the double bullet theory in the throat of the barrel. Testing of the material property’s of the barrel extension would be more difficult and expensive. As in the other failures that I have seen – the shooter was not seriously hurt. We will never know what happened for sure but this is my guess. Thanks for listening. mike Bykowski P.E.
I had same experience in 2000 with a Armalite. Winchester 748 (24) grains SMK 70gr Winchester Brass and Primer. Had shot this load over 500 times without issue. Last shot boom, blew out and into pieces magazine, broke bolt into two pieces, swelled bottom receiver and separated action into three pieces. Winchester requested ammo and tested themselves. Stated all were within spec then wrote me a check that covered complete rifle. I had it looked by rifle company, stated not their problem since I was using my own reloads. Never gave a reason to why it happened. Trip to ER to get some metal shavings out of my chin and cheek.
Like Florian says, need to look at the ammunition. Also, how many shots were fired before this event.
This highlights the need for education in reloading before people start. The Internet is only a starting place and Clubs and Associations are there to help.
And if you do not know what you are doing – useful factory ammo.
Root Cause Investigation will require full failure analysis of components and residue.
Try contacting this people http://www.reliability.com/index.html
They may create a training file after investigation.
Over-length cases can cause nasty things to happen, even with correct powder loads.
TRIM YOUR BRASS!
The scrap metal in question had more than an un-trimmed case, I suspect.
25 grains of Bullseye? That would be like stuffing a pellet of C-4 into the .223 case.
Bargain “Bulk” powder mis-labeled?
I doubt that there would be residual powder left in a thrower when changing from pistol loads (3 to 7 grains, for example) and twenty-plus grains of a proper rifle propellant. How many shuttles of the thrower hande take place whilst calibrating the charge on a set of scales?
What all this does indicate, is that when an “AR” blows, it is probably a lot less of a hazard to the firer than a typical bolt-action.
Firstly, because the action is essentially only open at the bottom, initial “gas leaks” go downwards, typically via the cartridge stack in the magazine.
Secondly, because the upper and lower are, (or should be) made from an Aluminium alloy (7075 or similar) forging, if a “Ka-BOOM!” occurs, it TEARS rather than shatters.
SCUBA divers will be aware of the horror stories about the old steel air tanks in wide use before aluminium became the norm. When a steel tank failed under pressure, it fragmented like a giant hand-grenade. The aluminium tanks flex and “bulge” before tearing open, usually in a straight line, along the length of the tank body. This is because, like a gigantic cartridge case, (or beer can), SCUBA tanks are produced by deep-drawing, and thus the “grain-structure” aligns with the direction of the drawing process.
This is why hydrostatic testing is done with the SCUBA tank submerged in a very large tub of water. The water also helps keep the metal cool as the compressed air is pumped in.