Quick Reload shortens reload times for ranged weapons. It is a Tier 4 Ranged skill that helps every gun, and it pays off most with slow-reloading shotguns and light machine guns.
Yes, it is a safe upgrade with no downside.
On The Move, Under Pressure and Up The Ante.
Shorter reloads matter most when a Horde is close. Get it before you take on the larger Hordes.