^ Those factors will affect shot placement with a .223 at distances much closer than 1000yd.
Out to 300yd the .223 is pretty controllable, but once you get out to around 500yd the factors listed above all need to be working in your favor to manage tight groups. Wind will be your worst enemy with a .223 at longer distances. Even the heavier .223 projectiles can destabilize when approaching 500yd which can produce some pretty inconsistent shot placement. Your most valuable tool will be a shot log. Record everything, wind speed & direction, temp, humidity, ammo, what you had for breakfast that morning, it'll all make a difference. Collecting shot data for reference will be invaluable in helping you understand how your rifle behaves in varying conditions...