Both of those indicators that Uncle Nick posted along with the annealing marks make separating 223 from 556 brass easy. I sort before I tumble so I can pick up on the annealing mark (at least that is what I think the discoloration is from). Obviously the 556 requires the extra crimp removal process before reloading. I just sorted about 600 cases this weekend after shooting with a buddy, all his were 556 loads and mine were all 223. I did get all of his brass since he doesn't reload. That may change after I told him how much my cartridges cost vs. his 556 even with the great deal he got on the 556.