The AR 15 flash can is a special muzzle device that directs the flash and sound from your shot forward, away from you and anyone nearby. This is especially useful if you have a short-barreled rifle (SBR) or pistol, where the shorter barrel can create a larger flash and louder noise. The AR 15 flash can is a special muzzle device that directs the flash and sound from your shot forward, away from you and anyone nearby. This is especially useful if you have a short-barreled rifle (SBR) or pistol, where the shorter barrel can create a larger flash and louder noise. The AR 15 flash can is a special muzzle device that directs the flash and sound from your shot forward, away from you and anyone nearby. This is especially useful if you have a short-barreled rifle (SBR) or pistol, where the shorter barrel can create a larger flash and louder noise.