Hi, you're doing a nice job in weapons, aileurs when you have finished this project, could you send me? So for textures, I use a rendering engine, I think you should have one in your program Blender ... if I'm not mistaken. However, account you use your weapons in the game, so I think you should use the UV mapping and texturing fun you have this one, otherwise, I also think that using a rendering engine, I actually Thea render explain in my tutorial here ==>
http://forums.qhimm.com/index.php?topic=16823.0 you could do rendering with textures create as I explained, and extract the 2D image obtained for place on your UV, I do not know the other 3D tools, so it's hard for me to explain to you, however, this Monday I'll start to learn ZBrush is the most complete and most powerful, and once learned I could help you a bit more than that