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.