RL-19 was made for 30-06. It and IMR4350 get the same results when loading 280.
If 4350 is good then IME R19 will do it better in the 280. R19 behind 140s in the 280 is the optimum powder for velocity. Don’t think you can push 4350 quite as fast. Accuracy is, as always, a different issue and depends on rifle. 4350 in the 06 is never a bad choice.
