My fault, I think. I was hand priming 338 Lapua brass with Fed 215m primers. I already primed about 30 pieces of brass when the whole tray exploded. Got a cut on my nose, burned my hands, blood blister on finger, knuckle is swollen and a cut on my knee through my jeans. I was extremely lucky. So what happened? The piece of brass I was priming was new Lapua brass, didn't feel any resistance while priming, at least no different than usual light pressure. I was not using proper technique though. I recently started tipping the device away from my face, just in case a primer went off. The manual clearly says to hold the tray horizontal to reduce the possibility of feeding multiple primers. It was a chain reaction detonation so all 70 primers in the tray went off at once. Wife is pissed there is a hole in the ceiling and it looks like someone set off a shotgun through the ceiling (primers ) Time to put safety first, wear the goggles and don't get complacent. Also time for a new priming tool.