I once witnessed a blown primer in an FN SxS shotgun. The gun did not have bushed firing-pins, and the gas-escape, in the right barrel, blew a large chunk of stock-wood off the side of the head, millimetres in front of the shooter's right knuckle.

It was I who found the errant piece of walnut, after everyone-else had stopped looking, about 25 metres away in the grass! Had it happened in the left barrel, we need have looked no further than the shooter's face!

I know of a .400 double rifle to-which this happened also. The splinter has since been glued back on. I offered to buy this gun, knowing that a re-stock would be required, but the current owner will take it to the grave apparently!

While neither of these incidents resulted in serious injury, it was only by the grace of God!