The accuracy of the infantry's blaster rifle decreases dramatically the longer you shoot. However, the first 3-4 shots will almost always be dead on target, making it a deadly snipe tool even over moderately long distances if you keep the bursts short. A great benefit that comes from sniping with the blaster rifle is the rapid fire which can give you up to three head shot points per kill if you're aim is on. For these reasons, selecting the sharpshooter is really only necessary for sniping over really long distances. On most battlefields though, the scope on the blaster rifle should suffice, also greatly improving your chances at close encounters.