I didn't have to do much workups to find a 1/2 MOA load. And while I consider my load of 74.3 acceptable, I believe i could do better.My father and I built 3 LRMs before the 28 was on the books. One for him one for me and one for my son. They all shoot 1/2 MOA fairly easily with moderate reloading effort. GW hit their target of a 180 VLD at 3000-3100fps with it for sure. It's biggest weakness is the single source for case and lack of factory rounds.
The rifle is good for 1500 IMO. I just have to drive a two hours to get to a place where I can shoot that, and with work & travel, that has been difficult.
With the 300 PRC, making your own cases just got a whole lot easier. Takes out four steps from the process of converting 375 Ruger. That is, as long as you can move the shoulder the proper length before resizing the neck. If you don't do it right, you will fold the brass, making trash.