KSL updated the article . . . strangely, they no longer mention the use of a gun to detonate the dynamite, and indicate that they don't know what triggered the explosion:
http://www.ksl.com/?nid=148&sid=6420831Rancher injured disposing of dynamite
May 8th, 2009 @ 4:04pm
By Alex Cabrero
BOX ELDER COUNTY –– A rancher in Box Elder County was seriously injured when he tried to get rid of dynamite.
Neighbors say Brent Larsen found the dynamite in his shed and was worried about it going off, especially with his grandchildren around. He took it out of the shed Friday morning, but for some reason––we're still trying to confirm that reason––the dynamite exploded, sending shrapnel into Larsen's face. Medical teams rushed to his Promontory home, but his injuries were so severe a medical helicopter was called to fly him to the hospital.
In the meantime, investigators were looking for any other pieces of dynamite that might not have exploded. Box Elder County Chief Deputy Kevin Potter said, "We need them to clear the area and make sure there's no other explosives before we finish the investigation, or really even get started investigating." The sheriff's office says when it comes to old dynamite, you should call professionals to get rid. Potter said, "The problem with old dynamite is that it starts to sweat and, once it starts doing that, it's in a very unstable condition, and it can go anytime."
If I remember right, when dynamite sweats, it release nitroglycerin, which is anything but stable (unless it's really cold).