I don't think I have any pics, but examine your necks for splits. Sometimes they'll occur right at the rim of the case mouth. Although, sometimes (depending on the caliber being reloaded) I'll continue using a case with a neck split.
THe case head separation usually begins with a partial ring, up above the "rings" that a full-length sizer leaves. To check, you can take a straightened paper clip and bend a small hook on the end. Sharpen that hook on a stone and use it to drag against the inside walls of the case. Don;t let carbon gunk fool you, but if a crack is beginning, and you're paying close attention, you'll feel it with the paperclip. On larger caliber cases I use a dental pick.
Alot depends on the caliber and condition of the rifle, too. A Savage 99 of mine, in 300Sav, will go from a good case, to very mild signs at the case head on the next loading, to a full crack or even a complete separation in the next firing. I've learned to load them light for that rifle and examine the cases carefully after each firing.
