The 300 PRC, 30-375R, will be a cataloged item with SAMMI in the next two weeks. I don't know how long it will take them to add it to their website. Dave Manson has the specs and can make anyone a reamer.
This was with new Hornady brass. COAL 3.700. Did a ladder test and the 77.1 & 77.4 looked really good/flat/low spread. No signs of pressure. Jumped up over 2,900 at 78.0 but spread opened up. I have loaded 4 rounds each at 77.2/77.3/77.4 to test ES/SD but waiting on weather. 8.5 twist heavy barrel 26in