I have come across a large quality of WCC-S brass and am going to use them in my Dillion 1050 and cut down to 300 blackout. From my understanding these casings were for training purposes only and used with paint rounds and etc. The S is to not confuse them with live rounds and the rim is smaller to fit in the smaller bolt carrier group for these training guns. the smaller rim and carrier group made it impossible for live rounds to be shot through these training guns. Since they are s brass they wobble in my Dillion 1050 shell plate and will have to go slow. my question is has anyone else use these casings for 300 blackout or 223 with any problems either with the Dillon or the rounds.