Armor Table

[Atgxtg]

I've been looking at the weapon damages and AP ratings did a little puttering around and came up with a forumula that seems to fit the data points for armored vehicles.

I was wonder how does this looks to people?

[table]mm(thickness)|AP

1| 4

1.2| 5

1.4| 6

1.7| 7

2| 8

2.4 |9

2.8|10

3.4| 11

4| 12

4.8| 13

5.7| 14

6.7| 15

8| 16

10| 17

11| 18

13| 19

16| 20

19 | 21

23 |22

27| 23

32| 24

38| 25

45| 26

54| 27

64|28

76| 29

91| 30

108| 31

128| 32

152| 33

181| 34

215| 35

256| 36

304| 37

362| 38

431| 39

512| 40

609| 41

724| 42

861| 43

1024| 44

1218| 45

2048| 48[/table]

Note this this would represent modern armor grade steel.

Weaker metals could be rates a few levels lower on the table, and some could take a hit vs. certain types of attack (like medieval plate worth 8 AP might be -4 APs vs. modern firearms).

This table is set up so that the firearms on the weapons table can just barely penetrate the armor that they can in real life, with a good roll, and not much more.

[Trifletraxor]

Could you add some examples too? Where real life armor in use fits into the table?

SGL.

[Atgxtg]

Could you add some examples too? Where real life armor in use fits into the table?

SGL.

Sure, a few.

British Mk I tank (WWI) Armor: 6-12mm = 14-18AP (Average 16 AP)

British Mk VII tank (WWI): Armor 16mm = 20AP

British Mk IX tank (WWO): 10mm = 17AP

British "Whippet" Tank: 14mm (max)= 19 AP

German A7V tank (WWI): 20mm sides 30mm front, but not armor grade steel so can probably drop AP by -2 to get 19 AP and 24 AP. (Average 21.5AP)

German Panzer IV tank (WWII): 10-80mm = 17-29APs (Average 23AP)

German Tiger II tank (WWII): 25-180mm= 23-34AP (Average 28.5)

US Sherman Tank (WWII): 19-91mm= 21-30AP (Average 25.5 AP)

US M3 Stuart light tank (WWII): 13-51mm= 19-27AP (Average 23 AP)

British Matilda II tank (WWII): 13-78mm = AP 19-29AP (Average 24 AP)

German Battleship Bismark: 50-320mm = 27AP-37AP (Average 32AP)

US Iowa-class Battleship : 190-310mm = 34AP-37AP (Average 35.5 AP)

King George V class Battleship: 136-374mm = 32-38 AP (Average 35 AP)

US M60 tank (1960+) : 150mm frontal = 33 AP

M1A2 tank: 650mm frontal = 41 AP

Russian T-80 tank : 335mm frontal = 38AP

BTW if we wanted to work facing in most tanks seem to follow a double rule, so find the frontal armor and get that AP rating. The sides are front -4AP. Rear is -8AP, and Top & Bottom -12 AP. Works pretty close for most tanks.

Or to simply. If you got the average AP score:

Front= +6 AP

Sides=+2 AP

Rear= -2 AP

Top/Bottom: -6 AP

[carnifex]

Hi!

this is a very good idea. I has to work on it for my vehicule rule.

with your permission of course.

carnifex:focus:

[Atgxtg]

Hi!

this is a very good idea. I has to work on it for my vehicule rule.

with your permission of course.

carnifex:focus:

Feel free. I'm using it in the latest version (4.2) of my Quick Vehicle write up rules and some uniformity between stats is always a good thing. I hope to be able to have something that people can download that will let them write up a real world vehicle in BRP terms in a few minutes. I'm just adding the armor table now, so people don't have to do the math.

If you want to put this on a spreadsheet the formula is:

Ln(mm of armor)x5.77+4

Hence the reason why I'm putting the table in.

Oh, and we could use this table for other materials by just applying a modifier to the final APs. Some rough numbers could be:

[table]Aluminum|-4

Bronze|-5

Soft (Not-Hardened) Steel|-3

Cement|-15

Oak|-18

Pine|-19

Sand|-27[/table]

It doesn't quite match up with the table in Call of Cthulhu, but for comparison:

[table]Material|CoC AP|Table AP

1 inch (25mm) Hardwood| 3 AP|3 AP

6 inch (152mm) Concrete| 9 AP |18 AP

2 inch (51mm) steel (not armor grade) plate: |19 AP|24 AP[/table]

Look suspiciously like they used +2 AP per doubling of the thickness in Co. That would be: Ln (mm) x2.89+8 as the base AP value

However, for what it's worth, in the real world a 7.62 isn't going to get though 6 inches of cement, but a .50 cal will do so.

[rust]

Thank you very much for this material, it really is very useful.

By the way, do you have any idea where Carbon Fibre and Titanium (the

two most common materials in my setting) could be in your table ?

Thank You !

[Atgxtg]

Thank you very much for this material, it really is very useful.

By the way, do you have any idea where Carbon Fibre and Titanium (the

two most common materials in my setting) could be in your table ?

Thank You !

Well, I'm still "guestimating" a lot of AP values while surfing for info on the net, but for a rough guess:

Titiatium would probably be about -1 AP (but at about 40% of the weight/ENC)

Carbon Fiber will be a little tougher to lock down.

The thing is that most of the lightweight synthic materials are not stronger than steel of a given thickness, but can give you the strength slightly lower than steel for only a fraction of the weight. And unlike most armors it can be make hard or soft and pliable.

Roughly, I'd say that it would have about the same AP as steal, but at about 40% of the weight, like Titanium.

Where it gets interesting is that since the armor is so light, you can make it thicker in some areas, like putting inserts into a ballistic vest to protect the vitals. So you could make the armor twice as thick, get a +4 AP bonus, and still be 20% lighter than steel.

Of course you can't always wear thicker armor. An APC can wear inch thick armor, and a battleship can have a foot of steel around it's belt, but neither is possible for a human being. You reach a point where it is either too heavy or too bulky.

We they get you on most advanced armors is at the cash register. Steel is cheap. Even the low grade industrial stuff can stop a bullet if you lay it on thick enough. Advanced ballistic polymers are expensive.

Hmm, I wonder what a suit of monomolecular mail, reinforced with a forcefield would be at?

[Joseph Paul]

However, for what it's worth, in the real world a 7.62 isn't going to get though 6 inches of cement, but a .50 cal will do so.

It doesn't look like the Army agrees with that. Penetration of concrete with M2 ball ammo is 2" at 200 meters. There appears to be a table giving the following in a FM- At 25 deg oblique and 100 m it takes 300 rounds to breach a 24" thick reinforced concrete wall and at 200 m it takes 1200. What is rebar reinforcement worth?

SLAP ammo appears to do about a third better in armor than M2 AP(I am presuming homogenous plate) so it may do about 3" of concrete but I don't have a source for that.

1" of concrete= Ln25.4*5.77-11? So 7.66 round up(?) to 8? .50 I am told will do 4d6+3 so 17 on avg. 2" of concrete should be about 12 AP so the .50 will still penetrate. The 7.62 does 2d6+3 (?) avg 10 pts. Hmm consulting my sources shows that the army believes that 7.62 mm *will* do 2" of concrete. How odd, I wouldn't have thought so. So this is close, at least for these two data points. Good call on the sand. Sand sucks to shoot through by all accounts.

Joseph Paul

[Atgxtg]

It doesn't look like the Army agrees with that. Penetration of concrete with M2 ball ammo is 2" at 200 meters. There appears to be a table giving the following in a FM- At 25 deg oblique and 100 m it takes 300 rounds to breach a 24" thick reinforced concrete wall and at 200 m it takes 1200. What is rebar reinforcement worth?

Which Army? If you are going to bring an Army in to disagree with me could you be specfic and yet me know who is disagreeing with what, or if you've just goggled up Garry's Infantry Reference Guide.

Also, I did say cement, not concrete, those rocks would make a difference, and rebar is a who different baby-especially if you hit the metal. That reinforcement is like a mesh that helps to spread out the impact.

SLAP ammo appears to do about a third better in armor than M2 AP(I am presuming homogenous plate) so it may do about 3" of concrete but I don't have a source for that.

That can depend on what gun you fire it from, and which version of SLAP. The regular .50 cal round have been tweaked over the years so that it now can get though an inch of steel, a lot more than it could a few years ago, when everybody was designing things based ion it being able to penetrate a half inch.

1" of concrete= Ln25.4*5.77-11? So 7.66 round up(?) to 8?

Round to the nearest.

.50 I am told will do 4d6+3 so 17 on avg. 2" of concrete should be about 12 AP so the .50 will still penetrate. The 7.62 does 2d6+3 (?) avg 10 pts. Hmm consulting my sources shows that the army believes that 7.62 mm *will* do 2" of concrete. How odd, I wouldn't have thought so.

As I wrote at the start of this I didn't go with average damage but with close to top end. The reason being that the spread for firearm damage is so wide, if I went with the average values then most bulletes would be able to get though some armors half the time.

For instance if the 50 cal can get through 25.4mm of steel at 200m do we set 25.4mm at the 17 average damage in BRP zero? or do we set it at the low end to be sure that it will always do so, and thus say that 25.4mm is equal to 6 points? Or do we set it near the top? I went with the latter. While it will mean that there will be times when a 50 cal won't penetrate something that it should, the other methods allow for lighter weapons to penetrate things that they shouldn't.

If the 7.62 penetrates 2" of concrete per your source (I'm not so surprised, since I don't think it was shooting at something 200m away for the test) then if the 7.62 does 2d6+4 (the bolt action rifle), then do we set 2" of concrete at 10AP? And if we do now the assault rifle (2d6+2) will be able to punch though 2" of concrete 28% of the time. And if we did that, the .50 cal which your sources (I assume Gary's) state can't penetrate 2" of concrete will now do so pretty much every time at 4D6+3.

And that is one of the big problems, Unless we want to throw out everything else and rewrite the combat rules, we are never going to get values that work right for everything. Even with a rewrite there would still be problems. There isn't one RPG that models modern ballistics perfectly. It's all very complex.

Do we want to do up weapon damage drop off by range? If so do we want to be accurate and model how some weapons drop off slower than others?

Do we want to get rid of the random die roll against armor so a firearm will consistently penetrate armor? Do we want to separate penetration form damage? Do we want to make sure that penetration still plays a factor since it is a major factor in the latter? For instance if we sett the 7.62 to, say Penetration 1D3+9, and then divided the total by 10 and multiplied it by 2D6 we would probably get a more accurate result, but it would be a pain to play.

Going back to your source and the concrete tests, that is another problem with weapons. Each weapon affects each material differently. So by your source a 7.62 is better at concrete that a .50 cal. But what about clay? Or brick?

For instace just looking at the .50 cal. data from Gary's:

[table] Range| Homogeneous Plate| Face Hardened Plate|Sand|Clay|Concrete

200m|25.4mm|22.9mm|355.6mm|711.2mm|50.8mm

600m|17.6mm|12.7mm|304.8mm|685.8mm|25.4mm

1500m|7.6mm|5.1mm|152.4mm|533.4mm|25.4mm[/table]

Now look at the drop off in penetration. For plate the penetration value at 1500m is about 30% of the value at 200m, for Hardened Plate 45%, Sand 43%, Clay 75%, and Concrete 50%. So, if this was done up for a game, each material would have to stop a different amount of APs at each range.

Any sort of universal chart won't work. IF we set if for one material and range it wont work for the others. For instance, I we set the damages so that a .50 cal will punch though 7.6mm of plate, and 25,4 mm of concrete at 1500 yards, then if we adjust that damage up for the bullet to penetrate 17.6mm of plate at 600m, and 25.4mm at 200m, the increase in penetration will carry over to the concrete and will end up going though 58.8mm and 84.9mm of concrete at the respective ranges.

So this is close, at least for these two data points. Good call on the sand. Sand sucks to shoot through by all accounts.

Certainly by the accounts of the folks who wrote CoC, where a "large sandbag" has more APs that 2" of steel plate. I wonder just how "large" that large sandbag is, and why we waste money on plate when sand is so much better. And in CoC a 9mm can get through 6" of concrete.

Now we certainly could tweak some of the values for the table. In fact I did say "roughly" I worked up the sand values based on the fact that 9mm and .45 ACP rounds tested did penetrate over 12" of sand in ballistics tests.

We could alter some values around. Make concrete -4 or kick up sand to -11 and see how it works for everything else.

[rust]

@ Atgxtg: Thank you very much for the info on carbon fibre and titanium !

[Celhan]

I really like this table.

I did a little ad-hoc 'Net fact checking with medieval and renaissance armor, and this table appears to hold up extremely well. The average thickness of breastplates is indeed just under two mm-- 8 points of armor, about what the BRP games I've read suggest it should be.

I'm sure you've done the same research yourself, but the fact that this fact-checks well with historical as well as modern armor hasn't been mentioned on the thread yet, and I wanted to give praise where it's due!

[Atgxtg]

I really like this table.

I did a little ad-hoc 'Net fact checking with medieval and renaissance armor, and this table appears to hold up extremely well. The average thickness of breastplates is indeed just under two mm-- 8 points of armor, about what the BRP games I've read suggest it should be.

I'm sure you've done the same research yourself, but the fact that this fact-checks well with historical as well as modern armor hasn't been mentioned on the thread yet, and I wanted to give praise where it's due!

That is sort of a surprise. I was thinking about modern armor and firearms. I fully expect medieval quality plate to be a little lower in quality, but that it would get a bonus vs. the slower moving weapons of the era. The two must be close enough on the chart to cancel each other out.

So something like:

-4 for Medieval Metalsmithing

+4 vs. archaic weapons

[Atgxtg]

I've dug up some more test data for the .50 cal.

This is firing at 100 yards (91m) as opposed to 200m+

Notice the penetration of concrete and sand.

From "The Ultimate Sniper"

by Maj. John L. Plaster, USAR (Ret).

page 222

Short-Range Media

Penetration by .50 Cal. AP rounds

Medium

/Penetration @ 100 yrds

_____________________________________________________________

CONCRETE (solid): 9 inches (228.6 mm)

TIMBER (logs): 96 inches (2438.4mm)

STEEL (non-armored):1.8 inches (45.7 mm)

ALUMINUM: 3.5 inches (91.4 mm)

RUBBLE (asphalt, soil, cement):20 inches (508mm)

TAMPED SNOW (19.9-24.9 lbs/cu ft): 77 inches (1955.8mm)

DRY SOIL: 28 inches (711.2mm)

WET SOIL: 42 inches (1066.8mm)

DRY SAND: 24 inches (609.6mm)

WET SAND: 36 inches (914.4mm)

DRY CLAY: 42 inches (1066.8mm)

WET CLAY: 64 inches (1625.6mm)

_____________________________________________________________

On the table, in Damage/AP terms that would be:

Concrete (solid) 229mm = 35 AP

Timber (logs) 2438mm = 49 AP

Steel (non armored) 46mm =26 AP

Aluminum 91mm = 30 AP

Rubble 508mm = 40 AP

Tamped Snow 1956mm = 48 AP

Dry Soil 711mm = 42 AP

Wet Soil 1067mm = 44 AP

Dry Sand 610mm = 41 AP

Wet Sand 914mm = 43 AP

Dry Clay 1067mm = 44 AP

Wet Clay 1626mm = 47 AP

SO if we go with non-hardened armor as -1 AP , and plugging that into the armor table we'd get:

[table] Material |AP

Concrete (solid)|-10

Timber (logs)|-24

Steel (non armored)|-1

Aluminum|-5

Rubble|-15

Tamped Snow|-23

Dry Soil|-17

Wet Soil|-19

Dry Sand|-16

Wet Sand|-18

Dry Clay|-19

Wet Clay|-22[/table]

[Joseph Paul]

Originally Posted by Joseph Paul

It doesn't look like the Army agrees with that. Penetration of concrete with M2 ball ammo is 2" at 200 meters. There appears to be a table giving the following in a FM- At 25 deg oblique and 100 m it takes 300 rounds to breach a 24" thick reinforced concrete wall and at 200 m it takes 1200. What is rebar reinforcement worth?

Which Army? If you are going to bring an Army in to disagree with me could you be specfic and yet me know who is disagreeing with what, or if you've just goggled up Garry's Infantry Reference Guide.

Why the US Army of course! The values I am refering to come from the appropriate Field and Technical Manuals for the weapons concerned. They just happen to have been compiled at Gary’s site but I have been tracking them down to cross check. And if you want to impugn a source because it is stored on a server you should be prepared to state why it is suspect. I find the “if its on the internet it can’t be valid” rejoinder ridiculous in the face of so much correct information being digitally stored.

Also, I did say cement, not concrete, those rocks would make a difference, and rebar is a who different baby-especially if you hit the metal. That reinforcement is like a mesh that helps to spread out the impact.

Do you have a cite for that figure for cement? I can’t find anything on cement alone. The Army manuals always reference concrete. I don’t know if they know there is a difference or if ‘concrete’ is supposed to cover both. I agree that the rebar makes a heck of a difference. I threw it in for completeness and to show that it is expected to be breached with concentrated, close range fire running into the hundreds of rounds. It sets an upper bound on what can be achieved.

Quote:

Originally Posted by Joseph Paul

SLAP ammo appears to do about a third better in armor than M2 AP(I am presuming homogenous plate) so it may do about 3" of concrete but I don't have a source for that.

That can depend on what gun you fire it from, and which version of SLAP. The regular .50 cal round have been tweaked over the years so that it now can get though an inch of steel, a lot more than it could a few years ago, when everybody was designing things based ion it being able to penetrate a half inch.

The stats on the SLAP and SLAP-T are pretty much the same. Do you know of a different one? My understanding is that the SLAP rounds are verbotten in the M82 and M107 rifles (problem with them coming out the side of the barrel (!)) so that leaves the M2 HB as the current weapon that can fire them.

Given the dramatic improvement of the SLAP round fired from the M2HB I extrapolated at what it could do in concrete. I could be wrong and I can’t find a source for SLAP penetration in concrete.

Quote:

Originally Posted by Joseph Paul

1" of concrete= Ln25.4*5.77-11? So 7.66 round up(?) to 8?

Round to the nearest.

Quote:

Originally Posted by Joseph Paul

.50 I am told will do 4d6+3 so 17 on avg. 2" of concrete should be about 12 AP so the .50 will still penetrate. The 7.62 does 2d6+3 (?) avg 10 pts. Hmm consulting my sources shows that the army believes that 7.62 mm *will* do 2" of concrete. How odd, I wouldn't have thought so.

As I wrote at the start of this I didn't go with average damage but with close to top end. The reason being that the spread for firearm damage is so wide, if I went with the average values then most bulletes would be able to get though some armors half the time.

For instance if the 50 cal can get through 25.4mm of steel at 200m do we set 25.4mm at the 17 average damage in BRP zero? or do we set it at the low end to be sure that it will always do so, and thus say that 25.4mm is equal to 6 points? Or do we set it near the top? I went with the latter. While it will mean that there will be times when a 50 cal won't penetrate something that it should, the other methods allow for lighter weapons to penetrate things that they shouldn't.

The .50 cal round that does that is the M2AP round. It uses a tungsten-chrome steel core rather than just plain steel one in the M2 Ball round. Why not give it an armor divisor or an amount of AP it bypasses to represent it’s special qualities rather than making it the basis of performance?

I believe that we should set the values so that the performance bears some close resemblance to what can be proven to be done. If we want to make the concious and informed decision to degrade or inflate the performance of the weapon(s) for genre or story reasons we can do that for the specific genre or story.We have discussed the problem you present hereand the solution I advocate is to spread the data points farther apart so that you do not get the overlap in performance.It means that a .50 will do a lot more dice of damage but that you won’t get less powerful rounds doing things they shouldn't.

If the 7.62 penetrates 2" of concrete per your source (I'm not so surprised, since I don't think it was shooting at something 200m away for the test)

It was and that is what is listed in table 7-3 of FM 3-06.11 for 25, 100, and 200 meters.

then if the 7.62 does 2d6+4 (the bolt action rifle), then do we set 2" of concrete at 10AP? And if we do now the assault rifle (2d6+2) will be able to punch though 2" of concrete 28% of the time. And if we did that, the .50 cal which your sources (I assume Gary's) state can't penetrate 2" of concrete will now do so pretty much every time at 4D6+3.

Whoa there Tex! You have got it all wrong, please go back and read it again. I claimed that there is no agreement to your unsourced assertion that the .50, in any configuration, would penetrate 6” of cement not that it couldn’t penetrate 2” of concrete. So lets look at your argument again. You claim that the spread for firearm damage is wide. I am assuming that you mean a specific die roll has a lot of variability to it, yes? Well that becomes less of a concern if the data points are spread out farther. I have discussed with you before the desirability of making firearm damages slope faster so that there is little to no overlap between clearly different KE of rounds. Additionally weapons with big damage using lots of dice will cluster statistically towards an average. Wildly high and low results become very rare. A side benefit is that you can have the room to express intermediate cartridges/different technologies/special rounds/ without running roughshod over the data point values or making each round very similar to the next. You rejected the argument on the grounds that it moves too far away from the values adopted from CoC for BRP.

And that is one of the big problems, Unless we want to throw out everything else and rewrite the combat rules, we are never going to get values that work right for everything. Even with a rewrite there would still be problems. There isn't one RPG that models modern ballistics perfectly. It's all very complex.

I agree that it is complex. I do not agree that we can’t pare down the inconsistencies that currently exist and keep it fairly transparent.As for rewriting the combat rules I think that it is time to seriously consider it. The firearm combat rules are a legacy of CoC. They may work very well for some people but it may be time to make a break with it and create rules that can capture the flavor of other genres better than CoC can. While such a thing is too late for BRP it might be doable for a supplement or a revision. I know, I know it sounds like sacrilage but I know that there are two kinds of gamers out there: those that care about such things and those that don’t. If the revisions cause minimal disruption to the play of those that don’t care why shouldn’t the rules evolve to serve both kinds of gamers?

Do we want to do up weapon damage drop off by range?

More than likely.

If so do we want to be accurate and model how some weapons drop off slower than others?

Perhaps. That information needs to be able to be presented on the character sheet in an intuitive format.

Do we want to get rid of the random die roll against armor so a firearm will consistently penetrate armor?

I want consistent pentration no matter how it is achieved. I advocate a two-step process. APs should be matched or overcome by penetration which is dependant on the velocity, mass, and construction of the round itself. Die rolls should reduce the HP of an object. I can see giving the armor a die roll once the fire is arriving at an oblique as an aid against penetration.

Do we want to separate penetration form damage?

Yes. See above.

Do we want to make sure that penetration still plays a factor since it is a major factor in the latter?

For instance if we sett the 7.62 to, say Penetration 1D3+9, and then divided the total by 10 and multiplied it by 2D6 we would probably get a more accurate result, but it would be a pain to play.

Yes that would be a pain but it isn’t the only way to model it. Can you explain how you derived that formula or were you just looking for something horrendous to present? How about a system where penetration is matched to AP and excess pentration become bonus dice of damage or a straight damage add. Douglas Cole has presented an idea for expressing armor as dice of damage that is soaked up from the weapon’s pool of damage dice. I need to find it again.

Going back to your source and the concrete tests, that is another problem with weapons. Each weapon affects each material differently. So by your source a 7.62 is better at concrete that a .50 cal.

That is not what I wrote. How did you get that idea? :confused:

But what about clay? Or brick?

For instace just looking at the .50 cal. data from Gary's:

Range

Homogeneous Plate

Face Hardened Plate

Sand

Clay

Concrete

200m

25.4mm

22.9mm

355.6mm

711.2mm

50.8mm

600m

17.6mm

12.7mm

304.8mm

685.8mm

25.4mm

1500m

7.6mm

5.1mm

152.4mm

533.4mm

25.4mm

Now look at the drop off in penetration. For plate the penetration value at 1500m is about 30% of the value at 200m, for Hardened Plate 45%, Sand 43%, Clay 75%, and Concrete 50%. So, if this was done up for a game, each material would have to stop a different amount of APs at each range.

Hogwash. The change in penetration is a function of the change in velocity at that range. All of the targets are struck at the same velocity at a particular range within the limits of manufacturing etc. The same energy is delivered to each target but each target handles it differently. The material sucks up penetration to overcome the material’s APs. Then damage is applied to the HPs of the object. Doing it the way you outline is more of a pain than supplying drop-off data for the weapons and counter-intuitive to boot. I mean really the concrete gets more fragile as we get farther away from it? Get far enough away and it will collapse on it's own!

Any sort of universal chart won't work.

IF we set if for one material and range it wont work for the others. For instance, I we set the damages so that a .50 cal will punch though 7.6mm of plate, and 25,4 mm of concrete at 1500 yards, then if we adjust that damage up for the bullet to penetrate 17.6mm of plate at 600m, and 25.4mm at 200m, the increase in penetration will carry over to the concrete and will end up going though 58.8mm and 84.9mm of concrete at the respective ranges.

You are right they don’t work. Let’s move on to something else. APs and HP per unit of material allows you to show the differences in the materials which is the important thing when dealing with breaking and penetrating materials.

So this is close, at least for these two data points. Good call on the sand. Sand sucks to shoot through by all accounts.

Uhmmm…the sandbag doesn’t have more HPs than 2” of steel. 1” of steel is 19 and the large sandbag has 20, at least in CoC 5th Ed. Did your finger slip?

Sand is better only when you don’t have to transport it. Besides plate’s APs don’t leak out when you do put a hole in it!

And that is a problem because 9s can’t really do that can they?

Sorry this reply took so long, I had some other things to attend to.

Joseph Paul

[Joseph Paul]

Hey looks like you found a source for penetrating 6+ inches of concrete! Congratulations! I searched that book with Amazon for a while but couldn't find anything on what rifle or round was being used. Did you see the figures for 5.56 and 7.62 at 100 yards?

If I understand the table in this post you give what the straight APs are from the Armor table for thickness and then give the material modifiers, right? If so why does everything have 25 APs? Do you realize that at 25 APs a 4d6+3 .50 cal fails 98.84% of the time?

Major Plaster does state that they are AP rounds so we could introduce a divisor or AP modifier to help with penetration. As the author points out what is hard is knowing how much 'oooomph' is left though. Hmmm.

Joseph Paul

[Atgxtg]

Hogwash. The change in penetration is a function of the change in velocity at that range. All of the targets are struck at the same velocity at a particular range within the limits of manufacturing etc. The same energy is delivered to each target but each target handles it differently. The material sucks up penetration to overcome the material’s APs. Then damage is applied to the HPs of the object. Doing it the way you outline is more of a pain than supplying drop-off data for the weapons and counter-intuitive to boot. I mean really the concrete gets more fragile as we get farther away from it? Get far enough away and it will collapse on it's own!

ohn Paul,

Look at the data provided @ Gary's:

[table] Range| Homogeneous Plate| Face Hardened Plate|Sand|Clay|Concrete

200m|25.4mm|22.9mm|355.6mm|711.2mm|50.8mm

600m|17.6mm|12.7mm|304.8mm|685.8mm|25.4mm

1500m|7.6mm|5.1mm|152.4mm|533.4mm|25.4mm[/table]

Now if the energy from a .50 cal drops off between 600m and 1500m (and it does) then the penetration for concrete should drop off. But it doesn't. The bullet penetrates just as deep into concrete at 1500m as at 600m, and that is all that the table covers, penetration. And the penetration value against concrete does drop off according to the test.

[Atgxtg]

Why the US Army of course! The values I am refering to come from the appropriate Field and Technical Manuals for the weapons concerned. They just happen to have been compiled at Gary’s site but I have been tracking them down to cross check. And if you want to impugn a source because it is stored on a server you should be prepared to state why it is suspect. I find the “if its on the internet it can’t be valid” rejoinder ridiculous in the face of so much correct information being digitally stored.

Being on the internet doesn't make information correct though. Especially official US Army documents. Generally the Army is very conservative about their performance data. So all all the armed services. According to Gary's a M1 tank is limited to 45mph. According to most experts and tank crews expect to hit 60.

I'm not impugning you source, just your claim that the "Army" disagrees with me. You made it sound as if the US Army stopped by, looked at the data and went "nope, no way."

Instead you looked at one source, took their data as gospel and then presented it as if you had an Army's to back up your judgment.

[Atgxtg]

[Quute=John Paul]

Do you have a cite for that figure for cement? I can’t find anything on cement alone. The Army manuals always reference concrete. I don’t know if they know there is a difference or if ‘concrete’ is supposed to cover both. I agree that the rebar makes a heck of a difference. I threw it in for completeness and to show that it is expected to be breached with concentrated, close range fire running into the hundreds of rounds. It sets an upper bound on what can be achieved.

[Atgxtg]

Whoa there Tex! You have got it all wrong, please go back and read it again. I claimed that there is no agreement to your unsourced assertion that the .50, in any configuration, would penetrate 6” of cement not that it couldn’t penetrate 2” of concrete.

1) I do have some sources for the penetration of concrete. So far all, you've brought up was Gary's.

So lets look at your argument again. You claim that the spread for firearm damage is wide. I am assuming that you mean a specific die roll has a lot of variability to it, yes? Well that becomes less of a concern if the data points are spread out farther.

No, not statistically. For instance, there is a certain amount of armor that a .50 cal will always penetrate at a certain range. Same with rifles and pistols. So if you set the minimum die roll so that you would get this vaule, it ends up messing the results against people.

If we did a wide range, liner progression you end up with the rifles doing so much damage that it becomes an autokill. Take a look at Mercenaries, Spies & Private Eyes. It uses a linear damage formula, and since a typical rifle has several times the energy of a typical pistol it does so much damage that it simply will characters outright.

That isn't how wounding works.

A 5.56 bullet has over four ties the energy of a 9mm bullet, but the mortality rates between the two are not at the same ratio.

I have discussed with you before the desirability of making firearm damages slope faster so that there is little to no overlap between clearly different KE of rounds.

Yes and you have failed to grasp the effects that has on characters. If a .45ACP can kill and is doing 1D10+2 and we have a 7.62 with six times the energy, and 13 times the energy/area, and have it do 6D10+12 or 13D10+26, it's wrong. Not with a fixed hit point system. BRP just doesn't handle location effects to a fine enough degree of detail. for that to work.

As I said before, it isn't "bang your dead". That is why the numbers wounded are so much higher than the numbers killed.

Additionally weapons with big damage using lots of dice will cluster statistically towards an average. Wildly high and low results become very rare.

They will perform with 3 standard deviations of the norm over 96% of the time. But the norm for the actual bullet and the norm for the die roll are two different things. For instance a standard deviation for 6D10 is over 7 points. So 1 standard deviation is a 14 point range. That is what will come up 8% of the time and to match that up with real weapon data we would need enough of a sampling for penetration data to get the actual spread of the real weapon.

A side benefit is that you can have the room to express intermediate cartridges/different technologies/special rounds/ without running roughshod over the data point values or making each round very similar to the next. You rejected the argument on the grounds that it moves too far away from the values adopted from CoC for BRP.

And still do. Even expressing intermediate rounds is meaningless if the game effect is the same. And a linear progression will have that effect pretty quick in BRP. The difference in pistol performance would be enough to hit an autokill zone.

And, of course there is the idea of doing this for BRP, not writing a new game system to support it. And signficantly altering the firearms data would mean altering the melee weapons too.

[rust]

If we wanted to be "realistic", we would need different tables for different

weapons and different ammunition types for both penetration and charac-

ter damage each.

A high penetration value does not necessarily mean a high damage value. In

fact, the best "manstopper ammunitions" are designed with a very low pene-

tration value, because the important part for damage is the amount of ener-

gy transferred to the body tissue, not the energy "wasted" for penetrating

it.

Any RPG simulation of real world weapons and ammunitions and their effects

on all common materials and the human body (not to speak of other creatu-

res' bodies - that would require even more tables ...) would become unplay-

able, I think.

So, instead of getting lost in details, we probably should concentrate on a

fast, slim and simple system for firearms combat - and I think the current

CoC system is good enough, and needs only few changes.

A good armor table is one such useful addition, a catalogue of penetration

and damage tables for all kinds of weapons and ammunitions is too much of

a good thing, I think.

[Atgxtg]

It is even more complex than that. It is different weapons have different penetration and damage ratings at differernt ranges, and it varies by material. And thats with out going into different loads. Since each bullet looses velocity at a different rate, and there is a variance from weapon to weapon, only a certain degree of accuracy is possible.

If fact it is so complex and has so may variables that there really isn't a all in one formula for tank gun penetration. All the formulas are innaccurate, or only work under limited conditions. That why they do testing.

Materials soak damage much better if the attack is slow as well. That is why leather and maille are effective against swords but no so effective against bullets. A 9.mm pistol round isn't doing much more damage that a broadsword, or have more energy. It just dumps it all in a smaller area.

Against people the ideal penetration range seems to be about 12" of flesh. Deep enough to reach some major organs and dump all thier energy.

I'm not opposed to doing things differently. In fact, overall, I'm not too keen on the values in BRP. Aps are so low that any heavy weapon can damage a tank, so some WWII tanks will kill a M1 at range, just that it will take two or three hits more.

But my goal here was to come up with a system that matches up with the values given in BRP.

There are quite a few other ways to tackle this, and I'm am planning on trying one somewhere down the road.

[Joseph Paul]

Now if the energy from a .50 cal drops off between 600m and 1500m (and it does) then the penetration for concrete should drop off. But it doesn't. The bullet penetrates just as deep into concrete at 1500m as at 600m, and that is all that the table covers, penetration.

Could this be an example of rounds performing sub-optimally at certain ranges? The 7.62 has a problem with sand below 200 meters for instance. Closer is not always better. I don't know, maybe you do, what the actual test parameters are for any of these figures. It may very well be that at 600 meters the .50 can zip right through 2" but not 3" while at 1500 m it is barely making it through 2" at all. I suspect that for the discrete materials like steel, brick, and concrete the test is against a sample of set thickness and not a monolithic block sample.

And the penetration value against concrete does drop off according to the test.

You have numbers for this? I would like to see the relationship.

[Joseph Paul]

Being on the internet doesn't make information correct though. Especially official US Army documents. Generally the Army is very conservative about their performance data.

I'm not impugning you source, just your claim that the "Army" disagrees with me. You made it sound as if the US Army stopped by, looked at the data and went "nope, no way."

Sorry for the hyperbole. Would smilies have helped?

Instead you looked at one source, took their data as gospel and then presented it as if you had an Army's to back up your judgment.

When a source as authoratative as the Army is involved what more do you really want? After all they actually did write the book on the matter. Is Major Plaster's data for penetration at 91m not derived from Army testing? I can't access the notes section but it does look like a standard test set up for the Army. In fact can anyone find non-Army data for these weapons?

[Joseph Paul]

1) I do have some sources for the penetration of concrete.

So source me baby, I want to learn more!

So far all, you've brought up was Gary's.

You still say that like it is a bad thing. Would it help if I attached the appropriate FMs? Do you have differing data at the 200, 600, and 1500 meter test points? And by the way I don't know who this John Paul guy is. My name is Joseph.

No, not statistically. <snip> So if you set the minimum die roll so that you would get this vaule, it ends up messing the results against people.

Please illustrate what you mean by a minimum die roll vs AP of 17. I think we are talking about different things.

As for killing characters I do indeed grasp what effect higher damages will have on them. However I agree with you that the present manner of deciding wounding and death does not tally with the reality of forensic ballistics. I can see a system where a round that doesn't hit something vital is mostly wasted. It may cause some small HP loss or bleeding but not an insta-kill. Under such a system you could have proper results for both endeavors- anti-personel and anti-material.

They will perform with 3 standard deviations of the norm over 96% of the time. But the norm for the actual bullet and the norm for the die roll are two different things. For instance a standard deviation for 6D10 is over 7 points. So 1 standard deviation is a 14 point range. That is what will come up 68% of the time and to match that up with real weapon data we would need enough of a sampling for penetration data to get the actual spread of the real weapon.

Correction in red mine. Do you suspect that the distribution for the actual bullet is not a normal one? That it would fall all within the first standard deviation for the dice roll? If it did what are we affecting by using dice results outside of that RW distribution? Currently you are already setting the penetration goal with out knowing what the distribution of the actual data is aren't you? Won't most of your penetration figures be greater than the mean and possibly crowding that first deviation break point?

[Atgxtg]

Could this be an example of rounds performing sub-optimally at certain ranges? The 7.62 has a problem with sand below 200 meters for instance. Closer is not always better. I don't know, maybe you do, what the actual test parameters are for any of these figures. It may very well be that at 600 meters the .50 can zip right through 2" but not 3" while at 1500 m it is barely making it through 2" at all. I suspect that for the discrete materials like steel, brick, and concrete the test is against a sample of set thickness and not a monolithic block sample.

I think what happens is the at long range the 50. cal had enough energy left to bury itself into the concrete and not much more. And that is mostly becuase it isn't going to bounce off of concrete. Plus, since concrete breaks up, it is hard to get penetration as much as how big a chunk it blows off.

One big difference between the tests is the range. All of my penetration figures are before taking anything off for range. Not for 200, or 600m down range. At at 100m a .50 cal can go through 9" of concrete.

That is alos why the 7.62 penetrates "better". It test data of 2" wan't done at 600m or 1500m.

If a bullet is going slow it deliever it energy more slowly. The gives whatever elastic properties in the target more time to absorb some of the impact. That's why a a bullet that wont penetrate a ballistic vest when it is worn, can do so if it doesn't have something soft behind it to soak up the impact.

It is also why old style armor doesn't work to well against bullets.

Plus, like I said, Army official numbers tend to be a lot lower that actual performance. GO find a couple of sources other than Gary's, including other Army sources and you'll see different numbers.

Opops. Typo it should have been:

"Now if the energy from a .50 cal drops off between 600m and 1500m (and it does) then the penetration for concrete should drop off. But it doesn't. The bullet penetrates just as deep into concrete at 1500m as at 600m, and that is all that the table covers, penetration. And the penetration value against concrete does not drop off according to the test.