I always did Ranged & Melee the same, you roll dodge/parry and every degree of success you stop one hit. However you only have one reaction per round, so you'll dodge the first guy's attacks but if targeted again you can't dodge or parry.

If you're trained to use your weapon, firing a shot into a place you want it to go isn't "challenging". Sure there may be things that make it challenging, but those are other modifiers that will adjust the roll accordingly. If you're just trying to hit something while standing still and taking a standard shot (which implies you are taking the same time to make one shot as opposed to many, so taking your time) then the chances are going to be in your favor.