Piercing -- pi-, pi, pi+ etc

[jtsmith1287]

So, I'm new to non fantasy gurps, and am going to be GMing a Mass Effect setting. I've never GMd a GURPS game (luckily the group is my wife, a co-worker and his wife, so no pressure) and can't for the LIFE of me find anything to explain the firearms piercing stat. I'm seeing things like pi-, pi++ ... the heck? I feel that I've read through the entire Basic Set just in search of this answer. So, feel free to link me to a page explaining this *in detail* or post an explanation. I will forever be in your debt.

[benz72]

How I think of it is just the size of the hole it makes.

Needlers, flechette, etc. Pi-

regular rifle/pistol rounds Pi

.50 cal BMG kind of stuff Pi+

Really exotic huge (20mm) stuff is Pi++

Anything bigger (spearheads) is impaling

[jtsmith1287]

Originally Posted by benz72

How I think of it is just the size of the hole it makes.

Needlers, flechette, etc. Pi-

regular rifle/pistol rounds Pi

.50 cal BMG kind of stuff Pi+

Really exotic huge (20mm) stuff is Pi++

Anything bigger (spearheads) is impaling

I just realized I did a horrible job at asking the question, haha. How do the game mechanics work with these stats?

EDIT: Nvm, Didn't see the previous post at first.

[coyote6]

B269 has the table explaining the abbreviations, and the text briefly explains the effects. B379 goes into details on the wounding modifiers of the various damage types.

[Agemegos]

Originally Posted by jtsmith1287

So, feel free to link me to a page explaining this *in detail* or post an explanation. I will forever be in your debt.

The basic rule is on page B.269, left column and B.379, right column; there are refinements dealing with special effects of different hit locations on page B.398–400.

To summarise: an attack might have an Armour Divisor, and will have a Damage Type, besides the dice and adds to roll. Once you have rolled a successful hit:

1. Check whether the attack does Large-Area Injury, and if it does calculate the target's effective DR using the rules on page B.400. Then GOTO 4.
2. If the attack doesn't do Large-Area Injury, and hasn't been targeted at a particular location then roll a hit location on the appropriate table on pages B.552–553.
3. Take the armour type on location and find its DR. It might have several listed separated by slashes ("Split DR" page B.282). If so, look up the armour in the Armour Tables —the notes will explain which ratings apply to which attack types— and choose the appropriate DR rating for the attack type.
4. If the attack has an Armour Divisor then divide the DR of the armour by the Armour Divisor unless the Armour is hardened, and if the Armour Divisor is less than 1.0 treat DR 0 as DR 1.
5. Roll the dice plus adds and subtract the modified DR. If this result is greater than 0 it gives you the penetration, and otherwise the attack has done no injury.
6. Check the location rolled in the text on page B. 398–399. Rule there might give you a wounding modifier to use instead of that for the damage type, or might modify that for damage type.
7. Multiply the penetration by the wounding modifier for damage type or hit location, whichever applies. Round fractions down unless the result is less than 1.0, in which round it up. (Page B.379) This is the point at which Damage Type has its main effect.
8. If the armour is flexible and the Damage Type is crushing, cutting, impaling, or any grade of piercing, and the armour blocked all the penetrating damage, you might (if the amount of damage stopped by the armour was 5 points or more of crushing or 10 points or more of any other type) get to do a few points for Blunt Trauma anyway (see page B.379)
9. The result is the amount of Injury or Wounding done by the attack, which you subtract from the target's hit points and assess for Shock, a Major Wound, Crippling, and Stunning using the rules on B.381 and 420–423.

Assuming that none of the complications having to do with large-area injury, armour divisors, hardened armour, or blunt-force trauma come into play, and ignoring for the moment interactions with split DR and with hit locations,

• pi- damage is halved after armour
• pi damage is as rolled
• pi+ damage is increased by half after armour
• pi++ damage is doubled after armour.

[Gollum]

Piercing damage has a history in GURPS.

In the third edition of the Basic Set, the term “piercing” just didn't exist. Guns made “normal” damage, that is, damage without any damage multiplier.

A pistol, for instance, inflicted 2d+2 damage (roll 2d, add 2 to the total, subtract the DR, and that's all).

Since there was no damage multiplier, exactly like for crushing weapons, the damage was noted with the “cr” abbreviation.

The damage of the pistol above was written “2d+2 cr”.

It was weird... And the GM was often obliged to answer players questions like “What? Guns do crushing damage? Like a mace? They don't do impaling damage like a spear? Isn't a gun supposed to make holes? And deep ones? Deeper than spears and rapiers, actually?”. “Yes!”, answered the poor GM. “Bullets do holes. But There is no damage multiplier, unlike spears or rapiers, because the amount of damage inflicted by the wound is already taken into account in the huge number of dice. It allows bullets to go through armors far much easily than spears or rapiers, exactly like they do in reality. Adding the impaling x 2 multiplier would be too much and using the impaling damage modifier with a reduced number of dice would also reduce this armor penetration power... Thus, the “cr” is just here to remember everyone that there is no damage multiplier. It doesn't really mean that it is crushing damage...”

But that is not all... After that, High Tech was published out, and with High-Tech, different kind of bullets appeared. Little calibers... Huge calibers... Then, some bullets began to have damage multiplier (x 1.5, x 2), exactly as other weapons... How to write them down? “cut” and “imp”? It became more and more weird and confused more and more new players and GMs...

The fourth edition decided to solve this problem by introducing a new term: “piercing”.

• Piercing (pi) just means that there is no damage multiplier, exactly as crushing.
• Piercing + (pi+) means that there is a x 1.5 multiplier, exactly as cutting. The weapon doesn't cut. It just do bigger holes than an ordinary gun.
• Piercing ++ (pi++) means that there is a x 2 multiplier, exactly as impaling. The weapon doesn't impale in GURPS terms (even if it does in reality – as every bullet actually), but it does very, very big holes due to a huge caliber...
• Piercing - (pi-) means that there is a x 0.5 multiplier. The caliber is very small and, so, the weapon is less effective than an ordinary gun.

It's more easy to understand. Guns don't do anymore crushing, cutting or impaling damage. They do piercing, or piercing + or piercing ++ damage. That's better, isn't it?

Just use these multipliers exactly as you do for crushing, cutting and impaling melee weapons.

Don't forget the armor divisor too, as very well mentioned above by Brett. Some bullets are specifically designed to get through armor, so they divide it's DR. But they are not the only ones to do that. Fragmentation grenades, some ultra-tech melee weapons also divide the armor DR...

This is not complicated.

1. Roll the dice.
2. Divide the victim's armor DR by the armor divisor of the weapon, if any – it's quite rare, actually.
3. Subtract the remaining DR from the dice total.
4. Apply the damage modifier and you've got the final damage that the victim suffers.

Example:
Weird Gun with a weird bullet (don't search it in the rules, it is just for the example): 4d+3 pi++ [2]. The victim wears a tactical vest with a DR of 12.
1) The player rolls the 4d+3... 19.
2) The tactical vest is divided by the armor divisor of [2]... 12 / 2 = 6.
3) 19 – 6 = 13.
4) Pi++ means a x 2 multiplier. So, the victim suffers 13 x 2 = 26 points of damage. That hurts!

[gilbertocarlos]

TL:DR?

Example: You shoot a guy, doing 3d of damage.
You roll 5, 4 and 3, 5+4+3=12
He is wearing DR4 armor, 12-4=8.
If your damage is pi-, halve it, becoming 4.
If it is pi, it is 8.
If it is pi+, multiply it by 1.5, becoming 12.
If it is pi++, double it, becoming 16.

[wellspring]

This is a good time to mention that this confused the hell out of me when I first learned the system. Details on the various damage types are spread across Basic Set: Characters. I finally ended up writing my own cheat sheet to make sense of it and put it all into One Big Table.

[TJA]

The one main GURPS problem :)
Too splattered rules ... and too few tables :D

[corwyn]

Originally Posted by wellspring

This is a good time to mention that this confused the hell out of me when I first learned the system. Details on the various damage types are spread across Basic Set: Characters. I finally ended up writing my own cheat sheet to make sense of it and put it all into One Big Table.

That's because Characters is for stuff that goes on character sheets. However, pg 379 in Campaigns has the wounding modifiers all in One Big Table - oddly enough, called Wounding Modifiers and Injury. It's under Damage in the index.

Now, it probably should be repeated in the tables in the back of Characters and on the screen, but that's another issue.