Upscaling d20 bullet damage

In a previous post tied bullet damage to the diameter of a round multiplied by the ratio of length to caliber in millimeters. This works fine for bullets which rarely go over 1 inch in diameter, and rarely have a ratio greater than 10:1 (which would max out at 10d12). I randomly mentioned this blog, and that got me pondering how the math would work out. Having looked into NATO Fox Calls for fighter planes, I came to realize that a large amount of weapon specs are available for US Munitions on wikipedia. I'm sure missiles are a bit more complicated than what is presented here, but I thought it would be worth the thought exercise. That being said, one note to mention is that in the previous post, the maximum size was d12 for 1". Most missiles are going to be more than one inch, and the inches should probably be multiplied separately from the ratio, but it seems easier to add the inches to the length ratio and multiply by that number. Both methods are shown here so anyone who wants to use them can use either method

Missile                     Dimensions (ratio) Damage

AIM-7 Sparrow (Fox-1)       ~8x144" (~x18)     d12x26  or d12x144

AIM-9 Sidewinder (Fox-2)    ~5x119" (~x24)     d12x29  or d12x120

AIM-120 AMRAAM (Fox-3)      ~7x144" (~x21)     d12x27  or d12x147

AIM-54 Phoenix (Fox-3)      ~15x154" (~x10)    d12x25  or d12x150

AGM-114 Hellfire (Fox-2)    ~7x64" (~x9)       d12x16  or d12x63

RPG-7 Round (~75x950mm*)    ~3x37" (~x13)      d12x16  or d12x39

AT-4 Round (~84x245mm*)     ~3x9" (~x3)        d12x6   or d12x9

Minuteman ICBM (~5.5x60 ft) ~5x60' (x11)       d12x785 or d12x46,800

Percentile Damage

You may have noticed that multiplying caliber and length separately produces damage in excess of 100 in all cases. It may be helpful to roll fewer dice and get bigger damage values. In that case, round the maximum damage to 100 points in whichever direction makes the most sense, and use that number of d100s. The following is the result of that.

Missile                     Damage Maximums    Percentile Roll

AIM-7 Sparrow (Fox-1)       1728               18d%

AIM-9 Sidewinder (Fox-2)    1440               14d% 

AIM-120 AMRAAM (Fox-3)      1764               18d%

AIM-54 Phoenix (Fox-3)      1800               18d%

AGM-114 Hellfire (Fox-2)    756                8d%

RPG-7 Round (~75x950mm*)    468                4d%

AT-4 Round (~84x245mm*)     108                1d%

Minuteman ICBM (~5.5x60 ft) 561,600            d%x5616**

"" with MIRV                ""                 use d30 for 3 shots,

                                               d20 for 5 shots,

                                               d12 for 8 shots,

                                               d10 for 10 shots,

                                               d8 for 12 shots,

                                               d6 for 16 shots,

                                               and d4 for 25 shots

Musings on Firearms in d20

A long time ago, way back before there were two kinds of Dungeons and Dragons, in an era where the first kind had only three editions, there was a modern version, with guns. It was sort of ok for generic purposes, but they ended up having to put out further supplements on additional firearms, both fact and fiction. That's all well and good, but ya know... it's probably out of print or something, and also you might not want to encourage piracy even if there aren't going to be particularly strong consequences for it. With that in mind, I came up with my own system for gun damage.

Damage Dice

Guns (and everything) deal(s) damage based on F=MV, but we don't need to complicate this. We can replace F with Damage, M with the size of the bullet, and V with a typical load of propellant. We don't have to even do it directly, we can just sort of provide a logical basis.

In this case, the M of the bullet is tied to its caliber, we'll assume that the following is true:

Caliber     mm           Dice
up to.25    up to 6mm    d4s
.26-.40     7-10mm       d6s
.41-.55     11-14mm      d8s
.56-.75     15-19mm      d10s
.76-1"      20-25.4mm    d12s

The V of the bullet is tied to its case length inasmuch as the case length defines what safe amounts of powder can be used to fire projectiles from it (actually thickness and material is more important than actual length, but it's a close enough abstraction for our purposes). To determine the number of dice, use (Case Length/Caliber in mm, rounding to the nearest whole ratio e.g. 9x19 Parabellum is 2d6 with 19 being 2.1x the length of its 9mm caliber. AK rounds (7.62x39) deal 5d6, and 5.56 NATO rounds deal 8d4. A .50 BMG being 12.7x99 makes it 8d8.  Likewise, a slug in 12 gauge is typically 18.5x70mm, which amounts to a ratio of 3.75, or 4d10.

Shotgun Shells

Instead of going into excruciating detail about how many different levels of buckshot and birdshot there are, we can just assume that buckshot or fléchettes reduces dice size by 1, but adds a 2 dice (6d8 instead of 4d10 for 12 gauge) birdshot reduces dice size by 2, but adds 3 dice (7d6 instead of 4d10 for 12 gauge), and Frangible reduces dice size by 3, but adds 4 dice (8d4 instead of 4d10 for 12 gauge).

Oh and one final thought: That original document may have propagated a myth that shotguns fire in a cone. They sort of do, but even at 150 feet you're only going to get about a 3" spread or so.

Weapon Actions

We will categorize weapon actions more broadly here for the sake of game rules--and because if we didn't a character with an M-16 can easily fire off their entire magazine in under a full round.

Single Shot

Covers breach action shotguns, flare guns, bolt action rifles, and single action revolvers.

• Each attack with this requires a single action (in PF2e) to bring a new round into battery

Semi-auto

Covers magazine fed auto-loader pistols, double action revolvers, lever action rifles, and pump action shotguns. 

• You can fire off as many shots as you can pull the trigger. It's a two action activity to multiply damage by 1d3, and a three action activity to multiply damage by 1d6. This costs 3 and 6 ammo respectively

Full-auto

Covers anything where one press of the trigger equals multiple bullets, including modified trigger assemblies that fire a second round when the trigger is released.

• With selector fire you may treat the weapon as a semi-auto
• If it's full auto only--or you've selected burst or full auto--you can still limit your trigger pulls to multiply damage by 1d6 with a single action activity (costing 6 ammo)
• You can multiply damage by 2d6 as a 3 action activity.(costing 12 ammo)

A Whole Damn Army Simplified

I have discovered a shortcut for making Group/Horde monsters into A Whole Damn Army of its own

If two questions would grant the same tag don’t worry about it. If you like you can adjust damage or HP by 2 to reflect the tag that would be repeated, but it’s not necessary.

What I'm about to tell you is strictly not RAW... but it is simple. You ready for it? Here Goes:

Take any Core example monster of Horde or Group organization sizes and add 1 instance of Uncanny Endurance (+4 HP) for every multiple of the party's number. So a party of 4-5 members fights a horde of 50 whatever as if it had 10-12 levels of Uncanny Endurance.

If they number more than 50 or so, you should probably also add Huge since a platoon is roughly 4 squads of 10. That and 50 people probably don't fit into a house. This addition is optional though.

For the purposes of Damage From Multiple Creatures, add +1 per Uncanny Endurance (equal to +1 per multiple of the party's population) rather than one per individual monster. If the party has allies that make the ratio smaller, don't increase damage as much as normal (to reflect the fact that some of the damage goes to the players' allies). So for example, in the above 10-12 levels of uncanny endurance, the party would take the full +(levels) of damage if they were the only combatants. If they had 20 allies though, the ratio is 2/5 so players would take +4 damage instead of +12.

Backstab: What I don't like about it and how I "fixed" it.

Let me just say it's not a bad move, but it has a few problems that don't really jive well with my idea of the fiction, and how I think thieves should work. Here's the default rule:

When you attack a surprised or defenseless enemy with a melee weapon, you can choose to deal your damage or roll+DEX. *On a 10+ choose two. *On a 7–9 choose one.

• You don’t get into melee with them
• You deal your damage+1d6 
• You create an advantage, +1 forward to you or an ally acting on it
• Reduce their armor by 1 until they repair it 
• Use a bit of gear for another effect that fits within the fiction

What got me even thinking about it in the first place is a player asked me [sic] "would that provide any bonus? sneaking around attacking a creature from its opposite flank? or would it be just the same as running up and punching it in its smug face?" Initially, I couldn't really answer the question, or at least didn't answer it correctly.

I said no, DW doesn't do that per se, your situational bonuses are in moves. But then I read closer "you create an advantage, +1 forward (etc)." Alright, that's all well and good, but they rightly pointed out "surprised and defenseless". So it dawned on me that the onus is upon me to determine every time whether a foe is surprised and/or defenseless, and I thought the way to do that was Defy Danger. I didn't like that.

Next there was "you can choose to deal your damage or roll +Dex", then choose 1-2 options, one of which is damage with a bonus, and a couple others have nothing to do with hitting anyone. So I  removed the redundant option, and wrote the following "replacement" move for use in my games:

Skullduggery

When you engage in tricky underhanded tactics, roll+Something*. *On a 10+ choose 3 different options. *On a 7-9 choose 2.

• You don’t get into melee with them
• You deal your damage+1d6
• You create an advantage, +1 forward to you or an ally acting on it
• Reduce their armor by 1 until they repair it(edited)

*Depends on how you describe the tactics.

It removes the need for me as a GM to define if the opponent is surprised (that can be an assumption behind "tricky underhanded tactics", but it doesn't have to be) and make the player roll Defy Danger. It doesn't force the player to strike immediately, and allows them to represent flanking or planning as appropriate with +1 forward. And finally, I prefer "choose 3/choose 2" over "choose 2/choose 1"

Is it broken? Probably, but I thought Backstab was broken in the other way (in being too narrowly defined).

Into the Heart of the Dragon

So I made a map for a Dungeo World campaign in which the party is swallowed by a dragon big enough to eat a village whole. The idea is that they escape the dragon by killing it from the inside, and it crash lands, This map is where the dragon crash lands.

Since the game also takes place in part, inside a dragon, I'll also leave you with the starter for the group inside the dragon:

World Eater was once a normal dragon. For many centuries now, the dragon has been so big it could eat a village. The additional size means the dragon does not have the same physiology as other dragons. Old tales tell of ancient heroes with legendary weapons could once pierce its scales, but nobody has succeeded in doing that as long as anyone can remember. Assuredly, larger holds survive by sheer volume of siege weaponry they can bring to bear. You are from no such land. Some of you may have been here a while, others only a month. This is your story.

First Impressions

Ø  World Eater was once an ordinary black dragon, but now has a variety of gemstones and minerals that have become embedded into the dragon due to its hibernation and feeding cycles.

Ø  The town of Gullet as far as anyone inside can reckon, is a little way past where the Dragon’s esophagus meets its trachea, hence the name. Occasionally the dragon eats, and the whole town shakes like an earthquake. Dirt and rubble from a new town becomes a part of Gullet.

Ø  Gullet is situated deep in a “valley”; deeply enough that when the dragon breathes fire, the citizens are not harmed. They do however feel an intense pressure wave.

Ø  Gastric Fog occasionally comes from “south” of Gullet, leaving those who are stuck outside with mild acid burns for the next several days.

Ø  There is something the villagers are not telling you.

Ø  A constant faint creaking sound accompanies a slight rising and falling, as if the entire area is in a constant tide.

Questions

(in addition to the bonds you make with the other players, answer +Wis of the following)

Ø  Are you on good terms with the citizens of Gullet?

Ø  How did you survive the fall from the Dragon’s maw to the town of Gullet?

Ø  How long have you been in Gullet?

Ø  What rumors have you heard about escaping the dragon?

Ø  Whence did you hail before your home was swallowed?

Ø  Who do you know in Gullet?

Ø  Who would try to stop you from escaping the dragon if you could get out of Gullet?