Doing a ladder test on my 222 Mag AI trying some AR Comp with 55 gr Sierra Blitz Kings. Loaded 4 five round batches. All batches functioned fine except the last batch. I had 3 out of the 5 rounds FTF. At first I thought my firing pin spring broke, nope. Tried about 6 times with each round, no joy. Finally decided it was bad primers as all the others went bang. I really hated that the last batch didn't work as the 2 that did fire went in the same hole! BTW, the primers were CCI BR4. I've been reloading for 50 years and never had this happen.