Howdy!
As written, ranged attack rolls are not modified by any character skill. My intention was to represent fast, desperate fighting in confined spaces where aim doesn't really matter so much as who puts the most lead/laser/plasma downrange the quickest. So I didn't think such a skill was necessary. Though, feel free to add a "Marksmanship" skill if you think it makes sense and would suit your game better.
Thanks for considering the system! If you do run it, I'd love to hear how it goes.