For those who missed it last time here are pics that show the results of the round going off in Pounder's 602 magazine.
The stock is cracked at the action
The cross bolts came loose
The magazine box is bowed, and although we didn't get a picture of it so is the hinged floorplate.
The ejector is bowed from gas flowing between it and the bolt body and there was a piece of brass from a cartridge between the ejector and the bolt body.
Dented primer on the burst cartridge
These are the 3 rounds that were in the magazine. For those who will say the problem was from an high primer, these were factory loads.
I've have not had any primers marked in my magazine from firing rounds over them in my 602, and 2 or 3 rounds are exposed to repeated firings as I often recharge the magazine without swapping out the bottom rounds. My rounds are longer than Pounder's .458, but I doubt that is the only reason for the problem. There are many 602's chambered in .458 and we haven't heard of this happening before. Given the number of these rifles used around the world, if the .458 versions had a problem we would know.