Hvy Barrel,
You might want to try RL19 and RL22 powders. I have had very good luck with them in 280 Rem, 280AI and 338RUM.
My gunsmith told me that RL22 is THE powder for the 280AI and I have to agree with him. I have a great load for the 160 gr AB but need to search for a better load for the 140 ge BT and AB bullets. I am going to try RL19 with the 140 gr bullets. After having great luck with RL19 and the 120 gr BT, I feel that its woth a try with the 140 grainers.
Tell me about your load and your rifle setup.
Regards,
JD338