The 223 is also good for 1000 yards. It's used in that distance in Service Rifle 1000 yard matches.
However you need a fast twist, 1:7, and 80 - 90 gr bullets. Those long pencil bullets need to be loaded long, they wont fit in the magazine, but in those matches you single load anyway.
They can be used in the deer/antelope class animals but you should us 60+ gr bullets and keep your hunting under 300 yards.
CPT USAR Ret
USAMU Sniper School Oct '78
Distinguished Rifle Badge 1071