That’s a great question, Ted. I’m not sure. Here's a couple examples of what I’ve listened to in several destinations about the Federal 210 vs Federal 210M discrepancies: I've been reloading for more than 35 a long time and have routinely switched amongst Winchester, CCI and Federal ( I purchase https://winchester-small-rifle-pr91234.actoblog.com/32473080/the-best-side-of-federal-primers-for-9mm