Additionally you have to use a firm Crimp right after seating on subsonic hundreds. I like Lee collet crimp . Crimp will enormously Increase the regularity and lower group sizing . Some pre-conceived and multi-level setting up is also crucial in deciding on 300BLK updates. By way of example, in https://300-blackout-once-fired-b34208.bloguerosa.com/37682045/the-best-side-of-300-aac-reloading