Is it possible to silence a projectile fired from a rifle (or handgun) that is supersonic?

Im pretty sure the movies get it wrong with the silenced 50cal sniper rifles as if the projectile is breaking the sound barrier then along the path of the bullet it produces a supersonic boom splitting through the air. Therefore if it is silenced at the muzzle and is travelling supersonic then it would still make a noise through the air making it not silent obviously