Bullet dispersion also varies based on whether you're hipfiring or aiming.

SMGs get a pretty big benefit to their accuracy from using the sights, so while there's a decrease in turning speed when you're doing it, learning when to use the sights makes Sharpshooter worth investing in.

Just a bit of speculation, but it might help the discussion. My guess is that CCP would choose to work in steradians when reporting the dispersion of a weapon.

There are two "most likely" scenarios for how this is calculated :

1) dispersion is calculated in linear units (like meters or feet) perpendicular to the bullet's flight path.

2) dispersion is calculated as a deflection angle.

Number 2 is more mathematically accurate and, imho, the most likely way for CCP to do the calculation even though it's more computationally "heavy" than option 1. The ramifications of this would mean that sharpshooter would be decoupled from the weapon skills, meaning that adding range through sharpshooter would not also tighten dispersion.

If method one is used, there are two ways to apply this effect. The first way would be to apply the dispersion distance at max range. I think this is unlikely though because, if this was the case, sharpshooter would improve dispersion by virtue of the fact that the "fixed" dispersion distance would be resolved farther from the shooter with sharpshooter skill, thus tightening dispersion. The second way of applying method 1,would be to apply the dispersion distance at some fixed distance from the shooter regardless of max range. This is functionally equivalent to method 2, and would mean that sharpshooter does not affect dispersion.