ah fuck it i give it up D:
Nothing works....

*Edit*
Lol it worked on my fucking shiity selfe made block gun...lol
dont know why...
Now i have to figure out how it works on othe rmodels

Here ya GO

How the hell can i get it done??
It always makes useless renders that doesnt match the uv and Nubs message didnt helped me D:

Honestly, it's a simple proccess.

Add a white material to your model,
Add a sky light anywhere,
go to Render>render to texture
add complete map
Render.

Huh? Are you saying I should try applying the UV map, render to texture, then doing the same with the white (or default) texture? Because it already had the texture on it, I just changed it to the default one.


*EDIT*

Ok, I've got it now. So, the deal is this:

First, you need to go to the objects Modifiers list, and select "Unwrap UVW" and make sure that the UV map of the weapon is that of the UV Map texture. Once that's done, you can go ahead and apply the white or default material to the object and render to texture.

The reason this works, and the other way didn't, was because there was no "Unwrap UVW" modifier present, so it assumed it had not been UV Mapped, and it creates it's own. This way stops it from making it's own (terrible) UV Map, and it simply renders it using the one present, ie, the one we want.