I made a flak script a few months ago, you can use it if you want:
----------init.sqs----------
[gamelogic1] exec "flak.sqs"
[gamelogic2] exec "flak.sqs"
[gamelogic3] exec "flak.sqs"
----------flak.sqs----------
_verz = 0.2
_obj = _this select 0
_pos = getpos _obj
_pos set [2, 1]
_pos2 = [(_pos select 0) + 1, _pos select 1, 1]
#start
_xdir = - 1400 + random 2800
_ydir = - 1400 + random 2800
_i = 0
_c = 50 + random 100
#schuss
? _i >= _c: goto "weiter"
_t = "bullet30e" camcreate _pos
_t2 = "bullet30e" camcreate _pos2
_t setvelocity [_xdir + random 10,_ydir + random 10,1500]
_t2 setvelocity [_xdir + random 10,_ydir + random 10,1500]
_i = _i + 1
~_verz + random 1
goto "schuss"
#weiter
~ 20 + random 60
goto "start"
Maybe its not exactly what you are looking for, give it a try and see.