This modifier applies to each individual attack you make (e.g. 64 units is equal to 1 yard, 70 units equal to 1 meter. For guns emptying their magazine (clip) within this second, the reload time is considered. a gun has a DMG of 10 and fires 3 bullets per second.
Some weapons deal additional bonus damage, either as AoE (see below), over time, or as EMP, affecting Robots and/or Power armor ('EMP (R)' and 'EMP (PA)' in the tables). This stat is most useful for comparing semi-automatic weapons such as rifles, where you can see the full damage caused by a single shot, regardless of how long it takes to load and fire the next one. For most guns, this is a single bullet, but for shotguns it is a single shell (containing several small pellets), for the Gatling laser it is a single beam, and for melee weapons it is a single hit. and shows the damage caused by a single click of the mouse/trigger. DMG: This information comes from the G.E.C.K.