The default birdcage flashhider on the M16A2/A4 and the M4 does a great job of hiding muzzle flash, even in poor lighting conditions. When the flashhider is removed or when a compensator is added, however, the muzzle flash can even become a huge fireball. There are usually two kinds of compensators/muzzle brakes: 1) those that dampen recoil but send the blast in directions that may be unfriendly and obnoxious to nearby friendly troops 2) those that increase recoil but project the muzzle blast forwards. The latter should rattle the senses of any opponent going barrel to barrel with that compensator.