People have been shooting bullets from .308 Win. cases winning 1000 yard matches and setting records with weights from 147 to 250 grains. You'll probably have the flattest trajectory with a 155-gr. bullet leaving at 3100 fps from a 32 inch barrel that will drop 280 inches at 1000 and have a wind drift for a 10 mph cross wind's 86 inches. A 240-gr. bullet can leave at 2200 fps and drop 480 inches at 1000 yards but has a 10 mph wind drift of 81 inches.
Lighter ones have less recoil and are therefore easier to shoot accurately. But the heavier ones can have less wind drift if shot fast enough. Most top competitors will pick the most accurate, easy to shoot well bullet over the one that bucks the wind the best. But a flatter trajectory does not mean better accuracy. All match bullet weights shoot the same accuracy wise from properly built and fed .308 Win. rifles regardless of their weight
Pick one. Then get the right twist, barrel length and chamber size for it, load up some ammo and go put a smile on your face out performing others who don't start off on the right foot.
US Navy Distinguished Marksman Badge 153
Former USA Palma Team Member
NRA High Power Long Range High Master
NRA Smallbore Prone Master