in my version you have three main instance variables :
ivDelay - so for example 0.1 means there will be a delay of 0.1 seconds before the next "burst"
ivSpread - this is the angle between each bullet - so 2 will move the bullets at 2 degrees from each other
ivNumber - the number of bullets
so if, for the three variables above (in order) we set 1 , 90 and 4 : would give a delay of 1 second before releasing 4 missiles at 90 degrees.
ivDelay 1,1,2,2,3,3,999 (the 999 indicates we have got to the end of the list and ...)
so first delay is one second, second "burst" would follow a second later, third 2 seconds after the second....
basically by altering these instance variables you can produce many various bursts - angles, delays and number of bullets.