Is it possible to use Unreal Tourn source code in my project?

Is it possible to use Unreal Tourn source code in my project?

Does it have some kind of license inbued to itself or can i use it freely in my projects as long as im using Unreal Engine? I have a special interest about the matter conserning the FPS artificial intelligence on that game source code, since i am already here, let me ask another question, how can i change the weapon only on the first person shooter example scene? When i try to do it, looks like the arm and the weapon are only one mesh