I would make a tutorial, but I wouldn't know what to put in it that couldn't easily be found in other tutorials. Most of my time would be spent finding good reference images anyway. One piece of advice I can give is it's easier to model things if you look for images of some of the individual major parts rather than the thing as a whole.
For example if I searched for 'M16' or something similar, I would likely get loads of pictures of it used in games (from the same angle), or somewhat blurry pictures of the gun in the hands of a soldier.
If I searched for 'AR-15 upper receiver', or 'M16A1 Handguard', I would get much more detailed pictures, generally closeups in sharp focus taken by people who are selling such things. I suppose that's most of the help I can give really.
Not really the best example, as searching for M16 seems to give some pretty good images. Even so, searching for those parts does give some somewhat better images.
Also, I made some more sights:
Ironsights
Aimpoint Comp M4
Eotech XPS3
Eotech XPS3 with an Eotech 3XMag
Trijicon TA648 ACOG
Schmidt and Bender 10x42 PM.II with generic mount.