tgjensen wrote:a) That's a matter of practicality, not rules legality. If I start at the edge of my deployment zone and you start at the edge of your deployment zone and they are directly across from one another then I will move so that I am exactly 18" or 12" away from you, because that must by definition be a full 6" or 12" move. I've never played anyone who actually intentionally placed his models at the edge of his deployment zone argue against that. Then again, I never played anyone who brought a SEM microscope to the table, so I guess we just play different types of people.
The point isn't that you can measure with that kind of absurd precision, it's that if you get into a situation that is only possible because of a measurement error (declaring a turn-1 charge with just a standard move 12" + charge 12") you don't get to claim the benefits of that measurement error. Even if the ruler says you're within range you fail the charge, just like if you accidentally roll too many dice for shooting you have to discard the extra ones and roll again.
(Of course the same would be true for failing a charge because of a measurement error. If your unit successfully shoots my unit with weapons that have 12" range but the closest model is not killed then if I move 6" and get 6" for charge range I'm making that charge even if I'm somehow out of range. The fact that you accidentally bumped a model backwards when you were rolling your dice doesn't mean you get to ignore the charge.)