223 rounds for my AR. I need to use Hornady 150gr BTSP bullets, but can’t find any information to support that. Working experience tells me the 550 press prefers a ball sort powder. Any idea wherever to begin? You will have to tweak subsonic handloads according to your rifle as https://israelylykv.blogdomago.com/37592255/not-known-details-about-300-blackout-bullets-for-reloading