Well, the lesson for the day is to wear your safety glasses with EVERY shot! Yowtch!! That does look about as ugly as it can get. I think JJ is right on point, and if you double click the pictures they come up full size and considerably magnified. No trace of a belt anywhere on the case, and the case mouth definitely still has a crimp in it. Yes, the box says 338 Win Mag, but if you really magnify the case head you can see the Hornady name in the lower right quadrant, and "maybe" the numbers 338 up towards 12 o'clock, but that's a pretty sketchy call. The lower left quadrant is still readable, and the last 4 letters appear to be "SPRP". That would mean it's the Hornady 200 grain SP-RP bullet, which conflicts with the SST labeling on the box. The problem is that there doesn't appear to be enough space left on the rim for 338 Win Mag. The other thing is the case is all bulged to hell above the rim, so whatever went in there was smaller than it should have been. The only guess I can make is a 338-06, and that would be about the right number of characters for the space on the case head..... If it had been that, there would have been a pretty substantial headspace problem because the 338-06 is shorter, so the firing pin could have kicked it forward and thus jammed the case neck in the lands. The neck of the 338-06 case is noticeably longer than the 338 Win Mag, so it would have stuck in the lands.
Check the links below and look at the case neck of the blown cartridge. It DEFINITELY looks like a 338-06 neck length, and seeing as the neck isn't split, it couldn't have been a 30-06.
http://en.wikipedia.org/wiki/.338-06http://en.wikipedia.org/wiki/.338_Winchester_MagnumIt would have been interesting to check every case in that box.