This mod changes a single value so that your gun will always point towards the crosshair - where you're looking. In vanilla the gun will not point towards where you are looking if you look up or down, preferring to level itself out. This makes aiming without right-clicking unintuitive.

As it only changes one value, it should be compatible with anything and everything. I made this mod after discovering that the file that someone had uploaded to the Nexus was hidden.


INSTALLATION

Either let Nexus Mod Manager do its thing, or move FirstPersonGunFollowsCrosshairs.esp to your Data folder and make sure it is loaded.

If you'd like to change this value yourself, open the GECK, go to Gameplay>Settings, search for FirstPersonHandFollowMult and change from 0.85 to 1, then save your .esp in your Data folder and make sure it is loaded.

Feel free to bundle this file (or use the method in the description) with any mod you are making and releasing. No need for credit, since I was just following instructions myself.

The Fallout New Vegas Version can be found here.

Thanks to LukeEndo, for commenting about how this is done 
http://forums.nexusmods.com/index.php?/topic/867473-gun-follow-crosshair/