Body Armor level DR

[Dewey]

In High-Tech and the Modern Warfighter Gear article Pyramid #3-57, they list stats for trauma plates which have DR 25 or 35. Based on the descriptions, the DR 25 plates are meant to represent the US Army's SAPI Plates, while the Advanced Trauma Plates in the Pyramid article, at DR 35, seem to be around the NIJ Type IV level. Based on that, what DR rating would NIJ Type IIIA and III plates have? They are intended to stop 10mm Auto/.44 magnum and 7.62x39/7.62 NATO respectively. Would the DR Value be based on the maximum damage produced by guns in that caliber, or the average damage?

[Kelly Pedersen]

Originally Posted by Dewey

Would the DR Value be based on the maximum damage produced by guns in that caliber, or the average damage?

Armor in GURPS is practically always based on stopping the average damage of what it's rated against, not the maximum. This is for a couple of reasons - first, it's more playable, giving weapon-wielding characters a chance, if they roll well, to have a chance of penetrating equivalent armor. Second, it's slightly more realistic, as well, since useful armor tests are statistical, performed with multiple trials and the ratings they provide are based on average penetration, not maximum.

Of course, the level of variability of damage in GURPS is where the realism bit kind of falls apart - in reality, the high-damage events that penetrate armor that's supposedly rated to stop it happen much more rarely than the GURPS damage mechanics suggest. You can just accept this as a place where GURPS goes more for cinematic than reality, or you can use one of the alternate systems that people have come up with over the years. Personally, I'm partial to Douglas Cole's "armor as dice" idea, which you can find in the article "Armor Revisited" in Pyramid #3/34.

[Anthony]

Note that, while penetration variability is much lower in reality than in GURPS, thickness of armor is much more variable in reality than in GURPS.

[fula farbrorn]

Also important is BFD, 2 vests rated to stop the same round, could have allow different amounts, For example NIJ allows for 44mm while GOST stops at 16

so a vest could reliably stop a threat its not rated for, but its BFD would be to high.... something i think wasent taken into account when the rules where written

[tanksoldier]

My experience is that commercially available armors rating is conservative. For liability reasons a vest is slightly overbuilt. Gurps is also slightly off in that a standard concealable vest at TL 8 is DR 12, which a standard 9mm can penetrate... but no 9mm round from a handgun is going to breach a modern vest.

Also the weapon being used is a factor. We lost a deputy a couple years ago to a .45 ACP which penetrated his vest... but it was fired from a carbine not a handgun. The vest would have stopped that round from any handgun length barrel no problem.

I don’t think Gurps models increased barrel length very well in that respect.

[Icelander]

Originally Posted by tanksoldier

My experience is that commercially available armors rating is conservative. For liability reasons a vest is slightly overbuilt. Gurps is also slightly off in that a standard concealable vest at TL 8 is DR 12, which a standard 9mm can penetrate... but no 9mm round from a handgun is going to breach a modern vest.

Fair enough and a problem with some armour, but in this specific case, the vest is giving the entire Chest hit location DR, despite the real coverage being only partial. It's an abstraction and saying that a high Dmg roll represents a hit outside the vest coverage seems as good an explanation as any.

Originally Posted by tanksoldier

Also the weapon being used is a factor. We lost a deputy a couple years ago to a .45 ACP which penetrated his vest... but it was fired from a carbine not a handgun. The vest would have stopped that round from any handgun length barrel no problem.

I don’t think Gurps models increased barrel length very well in that respect.

As far as I'm aware, GURPS Dmg is based on the actual penetration of a given round from a barrel of the length of the statted weapon.

Granted, High-Tech doesn't explicitly list every possible combination of high velocity ammunition and barrel length, but the fact that various +P and other high powered ammunition in 9mm or .45 ACP can reach much higher Dmg from a 16" barrel than a 5.5" is absolutely reflected in standard GURPS rules.

[Rupert]

Originally Posted by tanksoldier

My experience is that commercially available armors rating is conservative. For liability reasons a vest is slightly overbuilt. Gurps is also slightly off in that a standard concealable vest at TL 8 is DR 12, which a standard 9mm can penetrate... but no 9mm round from a handgun is going to breach a modern vest.

A modern vest that is brand new, etc. Also, unless you want to go to a much more detailed hit location system, GURPS gives most vests more coverage than they actually have. So if DR were to be increased to a "can't penetrate" rather than "stops average rolls" level, there would need to be more rolling for exact location hit, or a separate roll for covered/not covered.

Note that going to a "armour just stops stuff it's rated for" level of DR will make for fights many people will find frustrating and/or boring.

[Fred Brackin]

Originally Posted by Icelander

Fair enough and a problem with some armour, but in this specific case, the vest is giving the entire Chest hit location DR, despite the real coverage being only partial. It's an abstraction and saying that a high Dmg roll represents a hit outside the vest coverage seems as good an explanation as any.

Uh huh. I know of an incident c. 1990 where a SWAT team member in a full assault vest was killed by a single hit from a .25 ACP. It went in the arm hole and right to the heart. Gurps doesn't really cover that yet it's the sort of thing that happens in the real world.

[Icelander]

Originally Posted by Fred Brackin

Uh huh. I know of an incident c. 1990 where a SWAT team member in a full assault vest was killed by a single hit from a .25 ACP. It went in the arm hole and right to the heart. Gurps doesn't really cover that yet it's the sort of thing that happens in the real world.

How are Critical Hits not enough to model this?

There will always be some triple damage results and/or results where DR protects at reduced rate.

[Fred Brackin]

Originally Posted by Icelander

How are Critical Hits not enough to model this?

There will always be some triple damage results and/or results where DR protects at reduced rate.

I just now checked Campaigns and HT to be sure and I didn't see any result that would do the job.

Neither "DR protects at 50%" nor triple damage will get a pistol round rated for 1D P- though what should have been a DR 30 vest.

You'd need at last a "bypass all armor" (which result does not exist) followed by hitting the Vitals on a 1-in-6 folowed by rolling a 6 on the 1D6 damge with a failed HT roll for either the Major Wound or on passing zero and a final "bled out before the ambulance could get there".