I have loaded for quite a few creeds now and it is probably the easiest cartridge to find a load for.
I am currently shooting 124 gr Hammer Hunters over 47 grains of RL-26 in Alpha Munitions brass right around 3000 fps, grouping under a half inch.
I am doing some load development now with ADG Brass, 140 gr Bergers and H-4350. Due to havIng less case capacity and typically higher pressures, I don’t think RL-26 will work as well as H4350 or RL-16 would in ADG brass.
I have seen really good results with the Barnes LRX and H4350 out of Peterson Brass as well, under half inch out of a Savage Axis combo from Bass Pro.
I think overall the best bang for your buck powder in a 6.5 is H4350 or something equivalent.