It sounds like a a
double over-charged handload to me, but I could easily be wrong:
Authorities were called to the United Northern Sportsman firing range at about 2:19 p.m. on a report that a rifle had exploded after being fired. When they got to the scene, a 43-year-old man had fired a bolt action rifle with a 61-year-old man standing behind him. The rifle exploded, causing the bolt to be expelled from the rifle and hit the 61-year-old man in the chest.
The man firing the rifle suffered powder burns on both of his hands and injured both of his thumbs, one of them severely.
Be careful with both your guns and you ammunition, folks, and make sure both are kept in proper working order.