To Wound

For each Hit, roll a die to-Wound the model.

The basic number needed to-Wound is a 2+.

The to-Wound roll is subject to modifiers:

    If the model has Armor or Toughness, then the difficulty increases by 1 for each level of Toughness and/or Armor.
    If the attacker has a Massive weapon, then reduce Toughness for each level of Massive.
    If the attacker has an AP weapon, then reduce Armor by each level of AP. 
    Once Toughness or Armor is reduced to 0, neither Massive nor AP have any additional effect.

Example

Let us use some examples from Games Workshop’s Warhammer 40K universe, since most gamers are familiar with that background.  (Again, no challenge to their intellectual property is intended.)

An Imperial Guardsman with a lasgun (no special characteristics) hits at a Cultist (no special characteristics).  The to-Wound roll is 2+.

The Guardsman hits an Ork with Toughness 1.  The Ork’s Toughness increases the to-wound difficulty to 3+.  The same Guardsman then shoots at a Space Marine with Toughness 1 and Armor 2.  The difficulty increases to 5+.

The Guardsman equips himself with a bolter (Massive 1). He hits the same Cultist Ork and Space Marine.  The Massive has no extra effect against the puny Cultist, however, who is still wounded on a 2+ . The Massive negates Toughness but not Armor.  His to-Wound is now 2+ against the Ork and 4+ against the Space Marine.

The Guardsman now equips a Heavy Bolter (Massive 2, AP 1).  First he shoots the Ork.  The “extra” Massive has no effect on the Ork, and the Ork isn’t wearing armor, so AP is irrelevant.  His to-wound remains 2+ against the Ork. Then he shoots the Space Marine. The “extra” Massive has no effect on the Space Marine, either, but the AP removes one level of Armor. His to-Wound improves to 3+ against the Space Marine.

Geek Notes

I am working on the assumption that Hits are generally man-lethal.  If every target in the game was an unarmored human, then I would skip the to-Wound step altogether.  Flames of War does just that - for infantry, a hit is a hit.  FoW doesn't worry whether a .50 or a .30 is more lethal.  But our universe will have tougher and better armored things in it. So we have to worry about whether a .50 or a .30 better kills elephants and battle armor.  Hence we have Toughness and Armor.

The Warhammer series of games, by contrast, assume that, weapon Strength and target Toughness being equal, a weapon wounds on a 4+.  It must includes things like scrapes and near misses in the 50% of Hits that do not Wound, because otherwise it's pretty silly.  Think of all those chainsaws in the 40k universe!  I intend for cover saves to play a bigger role in my game than they do in the Warhammer series, though, so I'm sticking with 2+.

You will notice, however, that bigger, badder weapons do not get better at Wounding ordinary men. You never get better than a 2+.  So, in my game, some things are just overkill.   (This goes a long way towards explaining why even well-equipped forces carry ordinary rapid-firing small arms and not a zillion bazookas.)

Armor Piercing and Massive are separate characteristics, allowing a wider range of weaponry with different table-top performance. A weapon might be very high in one, and useless in another.  Think of an exploding shell that can tear a man apart but which cannot penetrate sealed battle-armor -- or of a thin intense energy pulse that punches through plate but can't stop a charging bull mastodon.