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Old 05-01-2017, 02:45 PM   #1
phayman53
 
Join Date: Dec 2012
Default House Rule for Realistic Armor Penetration

In this thread I mentioned a house rule that I have play with that seems to work pretty well for fixing the problem of muscled powered weapons penetrating armor too easily (which I believe is too high even at normal ST ranges and with most damage types, not just cuts). The design of this rule was based on a few premises. The first was that I wanted something that better approximated, in my understanding, the performance of various types of weapons against realistic armor. The second was that I wanted to change as little of RAW as possible, especially not wanting to rescale ST damage progressions. The third was that I wanted to make it as simple to implement as possible, requiring no or very few additional calculations during play. This rule is meant to replace the "Blunt Trauma and Edged Weapons" rule on pg 102 of LT, so it is not designed to work with it. Please let me know what you think!

House Rule for Realistic Armor Penetration with Muscle Powered Weapons:

Realistically it is very hard to cut or pierce armor with muscle powered weapons, much harder than the GURPS standard rules make it. Here is a revised rule:

1) All muscle powered weapons receive an armor divisor based on their damage type and weight distribution:

Balanced Cutting Weapons: (1/3)
Unbalanced* Cutting Weapons: (1/2)
Impaling Weapons: (½)^
Balanced Crushing Weapons: (½)
Unbalanced* Crushing Weapons: (1)
Piercing weapons and all other damage types: (1)
EDIT: All weapons that already have an AD have there AD halved, subject to GM customization.

*Unbalanced is any weapon that has a U in its parry statistic, all others (including unarmed attacks) are balanced.

^For added realism, some swords (Many spathas, Viking, and Oakeshott type X, XI, and XIII swords for example) and other kinds of weapons should have a thrust imp AD of (1/3)--basically, any weapon that does imp damage but does not have a very acute and stiff point. They tend not to thrust through resistive materials well at all. However, this may be too much realism for some people.

2) All Two-Handed weapons get an additional +1 to their damage values to represent the greater usefulness of these weapons against armor.

3) Even though armor was extremely protective against edges and points, blunt trauma could still get through it--especially flexible armor. The standard Blunt Trauma and Flexible Armor rule is replaced with the following:

Blunt Trauma Through Flexible Armor:
All Unbalanced Weapons do 1 point of injury per 3 points of damage stopped by flexible DR. This injury is never multiplied for damage type or hit location, but is added to any injury inflicted by damage in excess of DR.

All Balanced Weapons do 1 point of injury per 6 points of damage stopped by flexible DR. This injury is never multiplied for damage type or hit location, but is added to any injury inflicted by damage in excess of DR.

Blunt Trauma Through Rigid Armor:
All Unbalanced Weapons do 1 point of injury per 6 points of damage stopped by rigid DR. This injury is never multiplied for damage type or hit location, but is added to any injury inflicted by damage in excess of DR.

All Balanced Weapons do 1 point of injury per 12 points of damage stopped by rigid DR. This injury is never multiplied for damage type or hit location, but is added to any injury inflicted by damage in excess of DR.

Blunt Trauma through a Combination of Rigid and Flexible Armor:
The presence of rigid armor effectively makes all DR rigid. Use the rules for blunt trauma against rigid armor.

Example: Sir William the ST15 Knight swings his Thrusting Broadsword (2d+2(1/3) cut) at Sir Jean, who is wearing a fine mail Hauberk (DR4/2*cr). The effective DR of the Hauberk against this blow is 12. If Sir William rolls average damage he will do 9 damage. That means the Hauberk stopped his blow. However, his blow was powerful enough to injure Jean through the armor, doing 1 point of bludgeoning injury. If William rolls max damage he will do 14 cutting damage, which means he will defeat the DR by 2 cutting damage and deal 3 injury from the cut plus 2 bludgeoning injury, totaling 5 injury. If Sir William chooses to thrust instead he does 1d+3(1/2)imp damage, averaging to 6.5 damage. Not enough to penetrate the Hauberk’s effective DR of 8, but enough to do 1 point of bludgeoning injury. However, a max roll would do 9 damage, defeating the DR by 1 imp damage, resulting in 2 injury from imp and 1 from bludgeoning, 3 total. Such a thrust to the vitals would result in 4 injury instead. In all cases, the Hauberk prevented a major wound from a one hand blow from an exceptionally strong warrior.

However, if Sir William were using a mace, his damage would be 2d+4 cr, averaging 11 cr damage. This means that an average hit through Sir Jean's mail would do 9 damage, almost always a major wound! Furthermore, a max damage hit would do 14 cr damage, enough to put most warriors into negative HP.


Optional, Untested Situational Rules:

1) Armor that is braced against a rigid surface is significantly easier to penetrate. The Armor Divisors of every kind of attack is multiplied by 2 if the target is pressed against a rigid surface. This means that a balanced cutting attack would go from an AD of (1/3) to (2/3). Situations where this applies are:

1) Any time the target is prone or supine.
2) Any time the target is pressed against a sturdy wall.
3) Any other time the GM rules the target would not be able to give at all with a blow.

2) The head is vulnerable to trauma caused by sudden head movement caused by a blow, even if armor otherwise protects the head from all other damage. Any damage to a head hit location in excess of 50% of the DR on that location does 1 point of injury. This injury is not multiplied for hit location, but it does cause appropriate rolls against knockdown and stunning.

Last edited by phayman53; 05-01-2017 at 03:01 PM.
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Old 05-02-2017, 02:41 PM   #2
phayman53
 
Join Date: Dec 2012
Default Re: House Rule for Realistic Armor Penetration

This variant to the blunt trauma through DR rules in my first post. It makes it so that the DR of armor affects when a target starts taking blunt trauma, raising the minimum threshold for when a target starts getting injured. It is a little more complicated than the above rules to figure damage during play, but it is also more realistic and hopefully straight forward enough once you get some practice.

Alternate Blunt Trauma through DR Rule:
Armor starts letting blunt trauma through after damage has exceeded 50% of the armor’s effective DR (modified by any armor divisors). For every point of damage stopped by DR which exceeds 50% of effective DR, the target takes a fractional point of injury. This fraction varies based on whether the source of the damage was a balanced or unbalanced attack and whether the armor is flexible or rigid. In all cases, round fractions normally (<0.5 rounds down (minimum 0), >/=0.5 rounds up). This is injury, not damage, so it is never multiplied for hit location or damage source. Also, this blunt trauma injury is retained and added to injury from damage exceeding DR (the blunt trauma from the portion of the damage stopped by DR still injures even if the DR is defeated), but it is added after damage exceeding DR is multiplied by any relevant wounding modifiers. The fractional injury values are as follows:

-Unbalanced attack against Flexible DR: ½ point of injury/point damage greater than 50% DR which is stopped by DR
-Balanced attack against Flexible DR: 1/3 point of injury/point damage greater than 50% DR which is stopped by DR
-Unbalanced attack against Rigid DR: 1/3 point of injury/point damage greater than 50% DR which is stopped by DR
-Balanced attacks against Rigid DR: ¼ point of injury/point damage greater than 50% DR which is stopped by DR

If flexible and rigid DR are layered, count all DR as rigid (this may not be completely realistic but is for simplicity of play).

Example: In the same case as above, where Sir William (ST15) is attacking Sir Jean (Fine Mail 4/2*cr) with a swing from a thrusting broadsword (2d+2(1/3)cut). Sir William will average 9 cut against an effective DR of 12*, which means he will do 1 point of bludgeoning injury. A max blow will be 14 damage, resulting in 2 points of bludgeoning injury and 2 points of cutting wounds, resulting in a total of 5 injury. If Sir William thrusts (1d+3(1/2)imp he will average 6.5 damage against an effective DR of 8*. This means he will average 1 point of bludgeoning injury. A max hit will do 9 damage resulting in 1 point of bludgeoning injury and 1 point of imp wounding, giving him 3 injury total. A vital attack will instead do 4 injury total. The damage totals do not change in this case, but heavier armor would have an effect. Light layered cloth under/over the fine mail would increase DR to 6/4*, effective DR18* against the sword swing. This means an average hit would not do any bludgeoning damage (whereas it would still have done 1 injury in the original system).
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Old 05-04-2017, 03:58 PM   #3
phayman53
 
Join Date: Dec 2012
Default Re: House Rule for Realistic Armor Penetration

Another Example: Andre the Swiss Halberdier, ST12, fights an Austrian Knight wearing early 14th century Heavy Mail (DR5/3*cr). The Halberd does (with my modification above) sw+6(1/2) cut, sw+5(1/2) imp, and thr+4(1/2) imp. This means Andre does 1d+8(1/2)cut, 1d+7(1/2) imp, and 1d+3(1/2) imp [note: the main advantage of the thrusting attack is that it can be used as a stop thrust and it does not become unready after the attack]. So, on an average attack with the halberd's axe blade will do 11.5 cut damage against effective DR10*. This means he will do 2 bludgeoning and 1.5 cut, averaging to 3.25 injury. However, on a max hit he will do 4 cut and 2 bludgeoning, equaling 8 injury--almost always a major wound and crippling to a limb. The pick is similarly lethal, but in this case an attack on the vitals would average 3.5 injury and max at 11 injury. So, even an average hit from an average Halberdier will force -3 shock penalties against a well armored Austrian knight at the Battle of Morgarten, while 1 in 6 would be a major wound. The RAW optional rule for converting adds to dice would make max hits even more devastating, though they would happen much less frequently.

At this point I am considering changing the AD for unbalanced cut and imp weapons from (1/2) to (2/3) to make these weapons a little better against armor. In this case, the example above would change to effective DR of 7, meaning the average axe attack would do 4.5 cut and 1 bludgeoning, so 7.25 injury. The vitals shot with the pick part would do 3.5 imp and 1 bludgeoning, so 11.5 on average. Not sure yet if I like this more or not. However, with this change a 1 Handed Axe, sw+2(2/3) cut, from a ST 12 user would do 1d+4 (2/3) cut, so 7.5 (2/3) cut. On average this would get through heavy mail, though just barely. I'm not sure if I like this change or not. EDIT: It would also change these unbalanced impaling and cutting weapons to be more likely to get through helmets (Head armor often has many layers in GURPS), which they seem to have sometimes done according to chronicles and battlefield wounds, though this may be better represented by crits.

Last edited by phayman53; 05-04-2017 at 04:08 PM.
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