Over at a gun forum I frequent there was a post from a guy who was shooting at a range when another shooter experienced what in the industry is termed a "kaboom."  This one was a 357 mag in a Smith and Wesson handgun, and the shooter was luckily not really injured beyond a few cuts, but good grief, that is one catastrophic failure!  The reasons for the kaboom are unknown, but he was shooting handloads, so the most likely explanation is a double charge.  This is a good example of why wearing eye protection while shooting is a must.