I'm sorry. I read it as 100 feet. Not 100 inches. 12 inches is 24 yards, which is 72 feet, so 100 feet is well within range of a revolver.
I suppose he should use the Rifle, then.
On a side note, I did look it up and Ranged Data Systems does negate penalties for Multi Attack, not just ranged. It helps with any penalty to shooting. Not that I can make a multi attack action right now, but still.
I'll just use that first shot for his roll. With Ranged Data Systems, it makes the penalty only a -2. And I'll go ahead and double tap, since the Rifle is Semi-Automatic, which gives a +1 to the attack and damage, so it's only a -1. So his Attack Roll is an 11, and his damage is [roll0] + [roll1] + [roll2] +1. So 8. + [roll3] if he gets another one like before.