Think this version of your script is quicker...
; *****************************************************
; ammo2: Loadout for AssaultTeam
; Contains Magazines from :
; CORE
; *****************************************************
; EXAMPLE:
; Type this code into the INITIALIZATION box of the crate.
; this Exec "ammo1.sqs"
; *****************************************************
clearmagazinecargo _this;
clearweaponcargo _this;
; Get the parameters given
_This AddWeaponCargo ["Steyr", 5]
_This AddWeaponCargo ["M4ReflexSD", 5]
_This AddWeaponCargo ["M4A1Acog", 5]
_This AddWeaponCargo ["MK46", 5]
_This AddWeaponCargo ["RPGLauncher", 5]
_This AddWeaponCargo ["AALauncher", 5]
_This AddMagazineCargo ["SteyrMag", 10]
_This AddMagazineCargo ["M4ReflexSDMag", 10]
_This AddMagazineCargo ["M4A1SilencedMag", 30]
_This AddMagazineCargo ["M4A1Mag", 20]
_This AddMagazineCargo ["MK46Mag", 20]
_This AddMagazineCargo ["GrenadeLauncher", 30]
_This AddMagazineCargo ["RPGLauncher", 20]
_This AddMagazineCargo ["AALauncher", 10]
_This AddMagazineCargo ["PipeBomb", 20]
_This AddMagazineCargo ["Mine", 20]
EXIT
As this version doesnt need the initial array line.