First thought is... Don't Shoot It!  My guess is that the chamber is either in very rough shape or extremely large, and allowing un-natural expansion of the brass to the point that the sidewall splits.  Those split cases appear to be bulging!  The bolt face is pretty ugly, and the chamber (at least in my thinking based on that picture) may have some damage as well. 

I've seen split cases like that in a Russian Nagant, but in that case, it was more likely that the steel case was corroded from poor storage, and it only happened with one batch of Russian ammo (total of two cases).