Please some help explain how to edit/tweak weapons/character files

I have looked everywhere and tried everything ,but I can not tweak/edit the weapons and character files in Armed Assault. It was pretty easy in Operation Flashpoint, but every time I try to change anything in the weapons/character files, I get a crash. This includes the original weapons/character file or add on files. All I have attempted to do is make small changes in ammo power, accuracy and recoil of weapons and change the weapons carried by a soldier in game, from say a M16a4 to a M16a4 with Acog. Any help with this would be greatly appreciated. If someone has put out a guide on this, please point me to it. Thank you.