My father was hit in the upper back by shrapnel from a German mortar during WWII. He said it felt like he'd been hit by a brick, and that he thought (even though he knew that it wasn't possible) that it had "bounced off." He continued recording the location of mines in a minefield that had just been laid. (For any detail geeks out there, it was an engineer unit, laying a minefield to cover the retreat from the "bridge too far." One of the men got a little too anxious and set off a mine he was placing, and the explosion alerted nearby Germans to their presence. The platoon took 100% casualties.) Made it away from the area and back behind friendly lines before passing out from blood loss. (Interesting side note: the man who set off the mine was killed. His dog tag was found by relic hunters in the 1990s.)