just bought bushmaster

i just got a bushmaster ar15 to keep my colt company in the safe and i was wondering how to get the flash hider off of it its about 2 to 2 1\2 inches long and it has the crush washers behind it but no place for a wrench like my colt has do i put a punch through the hole and twist it off like a tee handle or does it evan come off {i hope }