One load I’ve found that has been MOA or better for 10 shots from ARs and bolt guns that have the twist to handle it is the 77 TMK, 25-27 grains of LVR powder lit by CCI450’s in a 223.
The reason for the variance in charge is the cases but I’ve been using 26.5 for quite a long time in my Dillon 550 I don’t even mess with the charge anymore. In an 18” upper it’ll run about 2775 FPS and man it’s a killer combo for anything I’d use an AR or 223 for.