How does one calculate Attack and Defense for missile weapons?

In ArM5, missile combat uses the same rules as melee combat. The attacker rolls an Attack total, the defender rolls a Defense total, and if the Attack beats the Defense, the missile hits. This is completely different from the way things were done in Fourth Edition. In Fifth Edition, all attacks, melee, missile, or aimed spell, involve opposed stress rolls. Calculating the Attack score is straightforward. Calculating the Defense score is a little special. First, the Ability to be used is the weapon skill appropriate to the weapon the defender is wielding. If he has a staff, he defends with Great Weapon skill; if he has a sling, he defends with Thrown Weapon skill. The hand-waving explanation is that weapon skills include the ability to avoid being hit, though meta-game reasons probably play a large part in the real explanation: the missile combat rules should resemble the melee combat rules for simplicity. Note that only shields, not other weapons, count toward Defense total against ...  more