An often overlooked area of the rifle involves the chamber mouth of the barrel in connection with case head projection.
by Norman E. Johnson
Here I will address an incident where a shooter experienced a partial case head blowout that released brass fragments into his face and right eye. At the time, the man was shooting a relatively small .224 caliber cartridge chambered in a Model 700 bolt action rifle. The load was well under maximum with no sign of excessive pressure noted on any of the previously fired cases. Cartridge headspace was normal. Extraction was normal and primer pressure signs were unremarkable. The case separation appeared to be a fortuitous occurrence and there may not have been anything he could have done to obviate the unfortunate accident, however, upon further examination the rifle and damaged cartridge revealed the apparent causes leading to the ruptured case head.
While there can be several causes of cartridge case head leak or blowout, I will isolate the more likely ones surrounding this particular incident.
Read more in our November 2014 issue. Back issues are available.