what are they

[viperdefender]

i was also wondering how accuate is the .223 and the .308 is and up to what yardage.

[CoyoteJack]

The maximum effective range of the .223 is around 500m. For the .308 it is around 1000m.

Accuracy though is more a function of the rifle and optics than the cartridge. For the actual cartridge consistency of production, bullet coefficient and such does factor in to some extent. The rifle itself is what is rated in accuracy when the MOA is listed or promised.

[Mity2]

While above statement is completely true, in general, heavier .30 caliber do tends to be more accurate when your reaching long distance say past 200~300yrds.
Faster, but much lighter .223 caliber tends to move alot with wind.
Heavier .30 cal will drop more as it travel longer distance. But to compensate drop is MUCH easier then compensate for variable like wind

[Xringshooter]

FYI, the AR15 is now the standard for shooting long distance at Camp Perry (the National Matches). The Garand used to be king but now if you are not shooting the AR you are going to be out of the money. They shoot up to 600 yds in these matches and are very accurate.

That said, both can be made to be very accurate at long distances. Although I very much like my AR's I would also like to own a Springfield M1A (M-14 look alike, but semi rather than select fire). It is a very accurate rifle.