Anti-Missile System

Introduced in 2617 by the Terran Hegemony, the anti-missile system is used to destroy missiles before they strike their target. This is accomplished by using a short ranged rapid firing weapon which shoots at the missiles. Because missiles in BattleTech are usually fired in salvos of up to forty at a time, anti-missile systems are rarely capable of destroying them all. Due to the loss of knowledge caused by the Succession Wars, anti-missile systems ceased to be produced by 2835. Only in 3040 did the Federated Commonwealth rediscover the means to produce this equipment. For the Clans, however, AMS never became LosTech, and by the time of the invasion, the Clans had improved on the Star League version by replacing the solid slugs with flechettes, allowing for more ammunition per ton.

Laser versions of the anti-missile system exist, and benefit from having no ammunition requirement unlike regular systems. However they produce heat as a side effect of their use.

There is also a version of the Anti-Missile System which has been configured to protect allied units within range of the equipped unit, known as the RISC Advanced Point Defense System.

Game Rules
The AMS, and Laser AMS both are capable of activating regardless of whether or not the crew is capable of fighting. When fired upon by a missile volley, and the incoming missiles are within the firing arc of the AMS, the AMS automatically fires to take down any incoming missiles.

If the missile volley is a "swarm type" or a multiple launched missile variant, such as a SRM-6 or LRM-20, the AMS forces a -4 modifier to the missiles rolling on the cluster table; Streak volleys are treated as an initial roll of 11 before this modifier. The modified roll can't be reduced below 2, unless players are using the Tactical Operations "Enhanced AMS" rule, in which case a result of less than 2 implies the whole missile flight is destroyed, and the defender takes no damage.

In the event the "volley" is a single shot type weapon, such as a NARC pod/beacon, or a Thunderbolt missile, then the AMS has a 50/50 chance to destroy the missile, with a 1D6 roll of 1 to 3 implying that the missile is destroyed, and a 4 to 6 meaning that the AMS was ineffective at stopping the missile. In this case the missile will apply it's effect as normal.

Lastly, if players agree, the AMS can be used as an impromptu Machine Gun, with the exception that the system can only fire into adjacent tiles. There are no range brackets for an AMS in this mode, except for short. Using the AMS in this mode in the fire phase will also prevent the use of the AMS to stop missile fire for that turn.

Models
The Anti-Missile System is manufactured on the following planets:

Burrow
The Burrow system proved to be susceptible to electronic jamming, however, and while the Star League Defense Force Quartermaster Command ordered their replacement with improved McArthur systems, most never had the chance to refit before the Amaris Coup.

McArthur
Originally developed by Mitchell Vehicles, the McArthur AMS is cited as one of the most popular models of Anti-Missile Systems in the post-Clan Invasion Inner Sphere. Despite being considered superior to other Star League era systems like the Burrow, the McArthur is not without fault. Models fitted to the Spartan were frequently prone to jamming when the 'Mech either ran or performed torso twists, ultimately the issue was traced to the placement at the Spartan's waist, with ComStar field engineers overcoming the issue during the Battle of Tukayyid by moving the system higher up in the right torso.

SureFire 444
Developed by Coventry Metal Works, the SureFire 444 (also rendered as the Sure Fire 444) is cited as one of the most popular models of Anti-Missile Systems in the post-Clan Invasion Inner Sphere, available over the counter to anyone with enough C-Bills.

Voelkers Parasol
Developed by Corean Enterprises, the Voelkers Parasol is cited as one of the most popular models of Anti-Missile Systems in the post-Clan Invasion Inner Sphere.

Yori Flyswatter
Developed by Yori 'Mech Works, the Yori Flyswatter is cited as one of the most popular models of Anti-Missile Systems in the post-Clan Invasion Inner Sphere.