59.5 H-4831sc is close to max in one of mine. 162 eld-x @ 2920. 25" pipe. It ran the 168 vld at 2850.
Getting 2930 with the other with RL22, but will be changing that soon, I don't care for the powder. Run's good, but inconsistent pressure signs.
Keep in mind if your new to the 280ai that the straight wall on the case won't create as much bolt thrust. Meaning that it won't show pressure on the head of the case as soon as a case with more taper will. Ejector marks on ai cases are bad news imo.
Start low and pay attention to brass life, if your loosing primer pockets in a few firings.....your too hot.
Be mindful of what you read and don't have any expectations of your velocity. There's a lot a bad info on this cartridge on the net, and a LOT of people posting velocities that can't be had without being over pressure. No reference to this thread, but I'm sure your reading others in your research.