From what I've found RL 23 loads are about 1 grain less than RL 22 in similar loading like 280 and 7SAUM. That's the route I went, 1 grain less than RL 22 max and backed off 10%. Should be shooting it in the morning.Just went through this myself, looked through all the forums and the consensus seemed to be to start loads in the mid-50 grains and work up to the high 50's. It actually yielded slightly higher velocities than RL 22 with same charge weights in my 23" barrel.
Also look at a magnum primer. Just start at the lower charges for a similar weight bullet with the 280 Remington. Do a 10 shot ladder to look for speed and pressure signs. There isn't much data for the Ackley Improved.I've been struggling to find load data for reloaded 23. I'd like to work up a load for my 280 AI using 160 AB or 162 ELD-X. Any suggestions?