i have some older 15 years + 1st. time firing rem. brass cases, they are splitting (1-6) small splits just above the shoulder, base of the neck very small apx. 1/16 in. called rem. help line. NO HELP ( brass to old.) they have no sign of high presure, can any one tell me what might cause this. i do load all my bottle neck rounds from 30-06 to 22 hornet and i have never seen any thing like this, i am afraid to reload them. i am shooting them from a ar 7.62 x 39 123gr. hor. sp. .310 dia. any ideas? THANKS