Hey I happen to be working on this blaster too! I did in fact use Nifskope to rip the in-game model. Thing is with game meshes is they are designed to be as low-poly as possible and all the detail is faked with bump maps, textures, etc. It is still great for getting all the major proportions right, though.
Here is the .obj ripped right from the game: dropbox
hopefully you can download from that link. lmk if not.
Hi franco, Really impressed with your work, especially the fallout laser pistol, the scratchbuilding skill demonstrated in that build is really quite something xD.