Purpose And Scope
The 2021 edition of "Warhammer 40,000: Kill Team" (KT21 for short) is a skirmish-sized wargame played with miniatures and dice. In KT21, it's a bit complicated to calculate average/expected damage for a shooting attack. Also, it's a bit surprising that improving the accuracy of a weapon by some proportional amount increases the expected damage by an even higher proportion. This post explores the quirks and nonlinearities of expected damage from shooting attacks.
Perhaps the most important thing to realize: number of attack dice, ballistic skill, and save characteristic all nonlinearly impact average damage (even if we ignore crit stuff). Attacking stuff super-linearly affects damage (increasing returns). Save characteristic sub-linearly affects damage (decreasing returns). Damage is hard to reason about.
For instance, doubling the number of attack dice will more than double the post-save damage. How much the post-save damage increases depends on everything else (BS, SV, special rules, auto-successes from cover, etc).
Update: I made my own KT21 Calculator.
