Hexum was apparently unaware that his actions were dangerous. Blanks use paper or plastic wadding to seal gun powder into the cartridge, and this wadding is propelled from the barrel of the gun with enough force to cause severe injury or death if the weapon is fired within a few inches of the body, especially if pointed at a particularly vulnerable spot, such as the temple or the eye. Although the paper wadding in the blank that Hexum discharged did not penetrate his skull, the wad struck him in the temple with enough blunt force trauma to shatter a quarter-sized piece of his skull and propel the pieces into his brain, causing massive hemorrhaging.
Wow.