Thanks to everybody for your responses -- even Frontline's trigonometric advice ...!

Your ideas make perfect sense...I've been a bit spoiled while playing a few other tactical simulations that provide target distances down to the meter, allowing for some effective micromanagement of offensive weapons of superior range. But then again...that was WWII armor...differences in range out on the Eastern steppe around 250BC aren't quite so great.

Time to practice and trust my instincts..."Use the force, Tarkus"...