Originally Posted by aeronyxjr.
You rename the texture and model files into the one you want to change it to. The texture alone will not change how the weapon looks, except for the skin of the gun, so you might want to rename the corresponding model files as well. However, this will create a change in file sizes and will require one of the bypasses which I have no clue about, nor do I give half a fuck. Ask supercarz or someone that apparently knows it.