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.
so ...
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.
Have fun