Also, those same rifles have muzzle brakes/suppressors, and weigh 18+ pounds.Now you know why the PRS guys are shooting 6mms.
IMO, spotting shots under 400 yards with a 308 shooting Mil-spec grade ammo, no brake, and any weight under 12 pounds is difficult. Even then, the scope would have to set at a lower power. When shooting steel, or game, while you may not see the impact, you will see the reaction from the target which will be milliseconds after impact. I do a lot of PRS and while my heavy weight, braked, 6.5x47L enables me to spot shots, I still need the scope set at a lower power for spotting the closer shots. It much easier to spot hits at 500+ yards because of the longer bullet flight time where it's more important should a wind correction be required, or the target is too far away to hear the hit or move the target.