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ASMRB House Rules

Version 1.5
January 9, 2000

13.0 Defenses

The DEF value of a given material is a measure of the specific energy required to destroy a given volume of the material. The tensile strength, hardness, density, and other properties of a material determine the DEF and Speed Class values.

13.1 Armor Materials

The Armor Materials list attached provides information about the defensive properties of various substances, in order to determine their DEF and Speed Class. The columns are:

Material:by name, in various categories
DEF 1 cm:the DEF value of a 1 centimeter thickness of the material
Speed:the Speed Class
gm/cm3:the specific gravity (density)
layer, cm:the thickness of a standard layer, for 'woven' or fabric materials
DEF layer:the DEF value of 1 layer
kg/m2:the mass of a square meter of one layer
comments:information for identifying the substance and its properties

Note that a 1 meter thickness of a material has a DEF value 23.3 greater than a 1 centimeter thickness.

In general, mesh/solid composites (such as fiberglass or reinforced concrete) have the Speed Class of the matrix (the binding material).

Mail mesh at 40% coverage(dense weave, such as double mail) has 4.6 less DEF than the solid material from which it is composed, plus an amount of DEF equal to the Speed Class of the solid material. 20% mesh mail (ordinary, or international, mail) will have 8.1 less DEF than the solid, still plus DEF equal to the Speed Class. Mail, like most flexible armor, has a Speed Class of Ø itself.

Example: flush with nuyen after a successful run, Agamemnon the Troll samurai orders a titanium mail hauberk. Double linked (40%), of course. The resulting armor has a DEF of (20 - 4.6) + 2 = 17.4 ~ 17, and is Speed Class Ø. This material will weight 9 kilograms per square meter; a troll sized hauberk covers 1.95 square meters. Thus, Agamemnon's armor will have a mass of 17.55 kilograms.

13.2 Aggregate Armor Value

Targets protected by multiple layers of armor material will figure the cumulative DEF of their protection as follows:

if both DEF are the same:add 4 points to DEF
if DEF difference is 1 point:add 3 points to better DEF
if DEF difference is 2 or 3 points:add 2 points to better DEF
if DEF difference is 4, 5, 6 or 7 points:add 1 point to better DEF
if DEF difference is 8 points or more:use better DEF value, unmodified

Complex, multiple material situations can be adjudicated by remembering that each doubling in the real amount of armor (as measured by thickness of a given material) adds 3.5 to the DEF. Speed Class of the aggregate protection can be averaged, rounding in favor of the material contributing the most DEF.

Example: the men of G Detachment, 1st ANGLICO, while traveling in an M113 APC, on a road known to be mined, place four layers of M69 ballistic nylon flak vests (individually DEF 12, Speed Class Ø) on the floor of the vehicle. The normal belly armor consists of 1.2 cm of Kaiser 5083 aluminum-magnesium alloy (16 DEF, Speed Class 1). Four layers of flak vests have 7 DEF more than 1 layer, thus the vests would total 19 DEF. Since the belly armor is 3 points less than this, 2 points are added to the DEF of the vests, for a total DEF value of 21. The referee rules that the net Speed Class of the belly armor, as a whole, is Ø, since most of the protective value comes from Speed Class Ø ballistic nylon. Note that this process requires over 50 M69 flak vests.

13.3 Area Values for Armor Coverage

When determining the mass of vehicle or body armor, the following area values and attached Armor Examples table should be used as guidelines. Body armor areas for average human adult male sizes are given (178 cm tall, 70 kg mass); generic 'very small' sizes (150 cm tall, 50 kg mass) are 20% less; 'small' sizes (164 cm tall, 60 kg mass) are 10% less, 'large' sizes (190 cm tall, 80 kg mass) are 10% more, and 'extra large' sizes (200 cm tall, 90 kg mass) are 20% more. Standard Shadowrun troll sizing (210 cm tall, 130 kg mass) adds 50% to human average. In case of doubt, round up.

armor piecehit locationsarea, m2
basic covert tee-shirt vest10-120.4
basic military vest9-120.8 - 1.0
extended tactical vest9-131.1
doorgunner vest9-141.2
jacket, hip length, includes collar7-131.4
hauberk, close fitting7-141.3
sleeves only, per pair7-80.5
boots, per pair17-180.3
helmet - M1 'pot' style50.15
helmet - PASGT 'fritz' style4-50.18
2 door, 4 seat compact car *1body12
 all windows total3.5
4 door sedan *2body21.5
 all windows total5.5

*1: this is based on the Austin Mini-Cooper 1275S; in the original vehicle, 250 kilograms of passengers, armor, and cargo could be carried; windows and floor are not armored)

*2: this example is based on a Mercedes-Benz 240D; as such, 500 kilograms of passengers, armor, and cargo could be carried; the windows and floor are not armored)

Example: the M69 vest is made of about 14 layers of ballistic nylon, and covers locations 9, 10, 11, and 12. Ballistic nylon is 0.28 kg per square meter, so one layer has a mass of about 0.24 kg. 14 layers would therefore be 3.36 kg; the listed mass of the actual vest is 3.78 kg in medium size - close enough for jazz, since the actual vest includes a bulky collar.

13.4 Armor vs. Stun

Use the reduced value (after Speed Class and Piercing modifiers) of any armor against the Body and Stun of an attack. If the reduced armor value falls to zero, then the character does not apply his or her own PD or ED against the stun of the attack (unless the character has Pain Resistance).

Example: Lt. Wilson (PD 5), wearing a PASGT Kevlar vest (14 DEF, Speed Class Ø), is hit by a 7.62x39mm bullet fired from an AK-47 (2d6 damage, +1 Stun, Piercing 6, Speed Class 2). The bullet strikes the chest for 8 points Body damage; the Speed Class difference and Piercing value of the bullet subtract 12 from the vest, leaving 2 DEF. 6 Body, and 30 Stun, get past the vest (Stun = (8x(3+1)) - 2). Since there was still a positive amount of resistant defense remaining, Lt. Wilson applies his own PD of 5 to the Stun past the vest: thus the final result is 6 Body and 25 Stun lost by the character.

When resolving non-penetrating attacks (did no BOD to the character) versus rigid armor (i.e. most materials with Speed Class 1 or better), double the reduced value DEF of the armor before subtracting it from the Stun done by the attack.

In cases where the armor is entirely out of contact with the character's body, such as large suits of powered armor, the referee should in many circumstances rule that no Stun will be done at all by a non-penetrating attack. On the other hand, crew of vehicles and powered armor suits should take Stun equal to the BOD taken by the suit or vehicle (after Damage Ignorance, that is) on penetrating hits: this represents 'being shaken up.' Only natural PD or other 'internal' (to the character) defenses can be applied against this Stun.

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Document last modified Friday, June 01, 2001