I've never had one either but I did witness one a few years back. Gun was undamaged but the shooter had to go to hospital and have a piece of lead removed from his hand. It was found that it was caused by loose fitting caps. Personally I just get frustrated with having to pinch No.11 caps to get them to stay on and as I said in my previous post I prefer No.10 caps on Uberti's and yes, some I have to remove with pliers but for me they usually ignite first time round and only occasionally need to be hit twice. I must have another look on Youtube as there is an American gunsmith who's done something to his revolver which guarantees the cap will split on firing, saw it years ago so can't remember what he did.