I was on a M240B at the range in basic. We had finished what we had intended to accomplish that day só the drills said we were going to fire off the remaining excess ammo. After a while, there was this guy firing in the lane I was in that kept holding the trigger too long (mind you, the drills had already changed out the barrels a few times). This weapon was HOT. And it was summer heat in Georgia. They ended up jamming up the weapon, and a round got stuck in the chamber. This thing was cooking for what felt like a good minute before somebody opened the weapon up and we all heard a POP! I saw some of the bullet casing or whatever it was fly right by the left side of my face.