I shot with a friend today. One of the guns he brought to the range was a new S&W 640. American Eagle 158 gn .38 SPL cartridges were splitting in the cylinders. Ejection had to be accomplished individually with my squib rod. The revolver's ejector would not budge the fired cases and we were not being ginger with it.
In total 30 of 50 rounds experience varying degrees of case cracks. Two different types of .357 ammo Winchester and CorBon ran flawlessly.