PDX1 in 7.62x39

I purchased some yesterday, tops of crimps all seem to have inline splits in case (4) where top edge meets projectile.They are a heavy 1/16th and seem to be uniform in placement , stopping at a step in top of case. All cartridges in box are like this with varying depths of split . Not too much info or pics on net, but pictures online didnt seem to have cut or step visible.Any info appreciated - Ed