Rl 22 imr 4831 4350 7828 and varget those will work find a starting load and work up I've never used Varget for the 6.5-284 but I think it will work but it will be a smaller charge than the others depending on bullet weight I would start with Rl 22 then imr4831 depending on case fill if the case gets compressed go too next fastest powder start low and work up allways use data and start low
RL22 is probably the least temp stable powder. Not something I would use in a hunting rifle, H4350, H1000, RL 26 23, retumbo, N560, N565, H4831 all worked great in mine 3 6.5/284 with a 4th rebarrel on the way now.
RL-23 & H-1000 will do just about everything you wonna do with a 6.5-284 24” 1:8 barrel accept with the 131 hammer hunters that’s a 1:7.5 24” barrel. Berger 156’s h-1000 55.4g 2920fps Hammer hunters 131gr RL-23 55gr 3155fps Berger 140 vldh RL-23 51.4gr 2880fps