I recently started reloading, starting with 300 BLK sub-sonic. To date I have had 100% success with sub-sonic. I am shooting through a 16” barrel with AAC Cyclone suppressor. Today I loaded my first supersonic rounds; using Nosler 125 gr. Ballistic Tip bullets, 17.8 gr of H110, CCI #400 primers and 2.060” OACL. Nosler lists the max. powder charge as 18 gr, which was the most accurate load that they tested. Everything worked fine, with the exception of the Lake City cases. Nearly all the LC cases blew the primers, some of the bottoms bulged and some had cut marks on the very ends. The Gorilla & PNW Arms cases all worked fine. In the photo below, the two PNW cases in the black tray were factory 147 gr loads. The two PNW cases in the black tray with gold primers tray were 220 gr. Subsonic reloads. Based on the reloaded Gorilla & PNW cases and fired primers, I am assuming that my Nosler supersonic loads are fine; and I just need to avoid reloading the LC brass. I believe that the LC brass came from some Freedom Munitions reloads I bought, as well as one other source that uses once fired LC brass. Any input is appreciated.