This is NOT my gun so I don't have all the details on the incident. This is what I do know. The owner was about half way through a concealed carry course when he experienced (what we believe to be) a squib load. What is a 'squib load'? It is when there is not enough energy behind the projectile to propel it through the barrel. Because of this the bullet will become an obstruction in the barrel. If you do not recognize the squib for what it is and fire another round you will force a catastrophic failure of the weapon a.k.a. KABOOM!
I do not know what type of ammunition he was using other than it was a brass cased full metal jacketed round. The shooter walked away with nothing more than a sore hand.
The shooter was using Winchester 'White Box' 95gr FMJ. He says during a string of fire he thought he experienced a misfire so he racked the slide inserting a new round. Not knowing that the previous round had gone off with enough energy to propel the bullet only halfway through the barrel and not enough to cycle the pistol. He then pressed the trigger on the fresh round which sent another bullet careening into the back of the stuck round...KABOOM!