Error message:-
_k = _unitArray select _j# error zero division
The script then either exits or gets trapped in the loop, it certainly doesn't progress.
Code:-
_unitArray = [sn2, sn3, sn4, sn5, sn6, sn7, sn8, sn10, man2]
_i = count unitArray
_j = 0
#loop
_k = _unitArray select _j
_j=_j+1
? _j >= _i : goto "next"
~0.01
? (("kozliceball" in magazines _k) and ("M60" in magazines _k) and ("PK" in magazines _k) and ("FALMag" in magazines _k)) : deleteVehicle _k
goto "loop"
#next
etc.