In a nutshell, not Aiming Down Sights (ADS) results in less damage over range, even with shotguns. As if we already didn't enjoy hipfire, this cements its place as a liability, in most cases. Obviously if you're in point-blank range, it doesn't matter.
A Fusion Rifle's Range Stat determines the Speed the Fusion Bolts will travel. The Range Multiplier granted from Zoom does not affect this, surprisingly.