They leave the barrel at around 1000fps. By time they get to 125 yds what are they traveling? 68 fps. Most snipers could probably duck out of the way when they saw the flash of the muzzle.
ballistic calc says 861 FPS @ 125 yrds with a 230 gr round nose at sea level and 0 degrees Fahrenheit temp.
Time of flight at that range is .41 seconds. So it is plausible for a sniper to duck under cover before the bullet reaches him, if he's really sharp.