TechManual (p. 204)
The anti-missile system (AMS) is essentially a rapid-fire, machine gun specifically used in a point-defense role. Designed to track, engage and destroy incoming missile clusters, the system proved effective enough for mass production, but is a terrible ammunition-hog. The Clan version tries to offset this flaw by using flechette-based munitions rather than slugs. This has allowed for greater ammo capacity per ton, but consumption remains a problem, and so even Clan AMS reserves tend to run dry after less than five minutes of sustained missile fire. Despite this, anti-missile systems have proven highly effective in space combat, where even larger missile classes can suffer from a cloud of point-defense fire.
Particularly popular Inner Sphere anti-missile system models include Coventry MetalWorks’ Sure Fire 444, the Yori ’Mech Works’ Flyswatter, Mitchell Vehicles’ McArthur AMS and the Voelkers Parasol produced by Corean Enterprises. These systems all weigh half a ton, and pack enough ammunition per one-ton bin for up to twelve volleys, based on consumption. The Clan versions run about equal in mass, but boast double the munitions capacity.
Any time a Missile Weapon makes a successful to-hit attack against a unit carrying an AMS, and the missile weapon strikes in the attack direction covered by the firing arc where the AMS is mounted, the AMS will automatically engage with the following results:
- The attacking player applies a –4 to the die roll result when rolling on the Cluster Hits Table (an AMS never reduces a roll on the table below 2)
- If the missile weapon is a Streak launcher, treat the launcher as though the controlling player rolled an 11 on the appropriate column of the Cluster Hits Table, then apply the –4 modifier to determine how many missiles struck the target.
- If the missile weapon normally fires only a single missile in a shot (such as a Narc Missile Beacon), roll 1D6: on a result of 1-3 the missile is destroyed, on a result of 4-6 the missile strikes the target.
The player cannot choose for the AMS to not engage, as it is always active until it runs out of ammo or is destroyed; 1 shot of ammunition is marked off each time the AMS engages a missile weapon.
If, in a single Weapon Attack Phase, more than one missile weapon successfully strikes the target in the attack direction covered by the firing arc where an AMS is mounted, the defending player can choose which missile weapon to inflict the modifier against.
Only 1 AMS can engage 1 missile weapon in a turn, regardless of how many AMS cover the attack direction. If a unit mounts more than 1 AMS that covers the same attack direction, the defender chooses the order in which they activate and against which missile weapons they inflict their modifiers.
AMS only works against weapons that are Type M (Missile Weapons). Weapons that lack this Type, regardless of their name or any other factor, are unaffected.Cluster Hit Table Modifiers:
The AMS Cluster Table modifier is cumulative with other Cluster table modifiers, for instance the bonus generated by NARC or Artemis IV-equipped missiles. In that instance, the net effect on the Cluster Table would be –2.Critical Hits:
Anti-missile system ammo explodes for Damage Value 2 per shot of ammo.Aerospace Units:
AMS against missile attacks from aerospace units operates as described above, with the following exceptions: for each AMS in the appropriate attack direction from an attacking aerospace unit, roll 1D6 and subtract that number from the missile’s standard-scale Attack Value before generating Damage Value groupings; AMS has no effect against Capital Missiles.