I think a GOOD .223 is fine for 300 yards. Or 600.
The calculated wind drift for a 175 gr .308 SMK at 2700 is 6.4" at 300, 28.6" at 600 yds.
The calculated wind drift for a 75 gr .224 AMax at 2800 is 7.0" at 300, 31.9" at 600 yds.
The calculated wind drift for a 90 gr .224 VLD at 2700 is 6.1" at 300, 27.2" at 600 yds.
(For 10mph crosswind per JBM)
I have shot all these loads. You might lose points by .6" with the .22 AMax, but you might gain by .3" with the .22 VLD relative to the .308. Me? I am not a good enough shot and wind judge for it to matter.
ETA: A 155 Scenar at 2900 beats them all in windage, but darned if I can tell a difference in MY scores.