Ive never used anything but Lapua brass. I just loaded some Winchester brass for my 243 and some of the primer pockets are extremely tight. I have to white nuckle the hand primer to get some of them in. When working up a load I noticed some black gas leakage around some of the primers on starting loads and up to full pressure loads as well. Could the leakage be because of the tight pockets? I reloaded some of the brass that leaked and the pockets are still very tight, so they did not expand.