I'm unsure if there is a mod like this, I'm not referring to Perfect Viewmodel, as all that does is change the translation of the viewmodel, what I'm referring to is the normal FOV slider, but one that effects how wide / narrow the gun looks to the camera.

Unless Overkill didn't make the viewmodel system like that to dependent from the cameras field of view, I just hope they did make it like this and is possible.