Musings on Ultra-Tech Gun Damage

Most people who regularly participate in my discord are either $3+ patrons, or non-patrons who just really like Psi-Wars, but I have a few that are only $1 patrons and thus have only a passing interest in Psi-Wars, but mostly strip-mine my material for their own campaigns, which is fine!  That's part of the intent of what I'm doing. But a lot of my material lately has been more "Psi-Wars" specific, and not especially generic at all.

One such poster mentioned "Gauss Guns" as an off-the-cuff example of something more useful to him than what I had been posting (though I hasten to add that it wasn't meant to diminish what I was posting), and that single line got me thinking about something I honestly dread: Psi-Wars needs guns.  There are several reasons for this, but most of them revolve around illustrating a more primitive era, from the 40k-esque Mug to the hunting weapons of Nekotara, to the ancient weapons of the Tyranny, one way you can show that a particular race is ancient is to give them firearms rather than blasters (especially given that firearms are pretty much better than all beam weapons until Blasters show up, which means they can "keep up" nicely).  But this poses another problem, because the point of the Mug is to have extreme ST and to showcase what you can do with it, and part of the idea there is to give them arms and armor that take advantage of their superior ST.  So it's not enough to use the existing weapons, which are built for ST 10, SM +0 humans, because I need guns built for ST 20, SM +1 dragon-people.

So I need to be able to design guns.  And I don't have a system for it.  But my conversion of GURPS Vehicles gave me hope: it looks like most 4e vehicles are just 3e vehicles with some minor tweaks to a couple of formulas that we're largely privvy to, and a few arbitrary values chosen by the designer based on his assumptions for the vehicle.  Could the same be true of guns?

There are a lot of stats for guns.  The following, I think, can be arbitrarily assigned:

• Malf
• Acc
• Bulk
• Rcl
• LC

I suspect there's a formula behind Acc, Bulk and Rcl, but I think it's safe enough to make some basic, arbitrary assumptions: Pistols are Acc 2-ish, rifles are Acc 4-ish, and cannons are Acc 6-ish; rcl is generally 2, but it might hit 3 or maybe even 4 for extremely unwieldy weapons.  Guessing at bulk is more involved, and we need to get a sense of the weight and length of the weapon, but we'll come back to that.  But if we know these parameters, we can compare the weapon to existing weapons and make a reasonable guess.

The following are likely derived from formulas:

• Dmg
• Range
• Weight
• RoF (or at least, from design choices)
• ST
• Cost

For guessing at how these formulas work, I'm going to use Ultra-Tech exclusively.  I suspect LT and HT weapons aren't derived from formulas, but from real world stats converted into GURPS.  Thus, the only place where I think we can see a design system in action is Ultra-Tech, and that makes sense, as there are no "real-world" weapons from which the stats can be converted.  And this makes sense: if we want a gun design system it's for arbitrary weapons, like "What does a pistol for an SM +1 dragon-man look like, anyway?"  And I'm going to start with damage, as that's the most important, though we'll quickly see that the variables that matter to damage here will impact the values of other stats elsewhere.

Whenever I post something like this, someone inevitably responds with "But don't you know about X?" Someone somewhere has made a conversion, or worked out some formula and posted it somewhere on the internet.  To that, I say: Bring it.  I can use any help I can get.  I've done quite some research on this topic, and it's something I've been chewing on for a long time, so I may well know about it, but shoot it my direction anyway, or leave it as a comment, so other people can see it.  Every little bit helps, and it's safer to assume I don't know and annoy me with things that I've already seen than it is to assume I do know and then I miss the valuable, secret answer.

So, without further ado, let's look at gun damage.

Damage in GURPS Vehicles

So, as our starting point, we'll look at the formula for damage in GURPS Classics: Vehicles. It's almost certainly out of date, but it'll serve as a good starting point.  We can find the formula on page 104, which I will replicate for the sake of our discussion.

KE DAM = B × L × G × T × P

Here, "DAM" is damage in dice, "B" is bore-size in mm, L is a value based on barrel length, G is what sort of gun it is, and we can dispense with that for now (It'll be more pertinent when we get to gauss, but I suspect gauss is going to take a lot more work than conventional, as there are two different versions of gauss floating around, and I'm pretty sure that Pulver's gauss stats in UT are heavily massaged for gameability), T is a value based on tech level, which we should presumably boost given that we're using advanced, ultra-tech weapons, but we'll leave at the TL 6+ level for now.  Finally, P is how much "power" the round has.

So, the main stats we find ourselves concerned with are bore size, barrel length, the power of the round and maybe a single multiplier that represents advanced technology.  Do these stats make sense?

Bore Size

Bore size is fairly easy to derive from our guns if we want to test our weapons and is the most useful measure for us, as it determines what rounds we can fire (I'd rather not build my own rounds, thanks, though we'll come back to WPS and CPS later).  But here, it has a linear relationship with damage: if you double the barrel size, you should double damage.  Is that accurate in 4e?

On page 25 of Pyramid #3/27, Mark Gellis (a man who may well be inducted into the mysteries of the One True Gun Design System) claims that a 160mm warhead does 4 times as much damage as a 40mm warhead, and that a 400mm warhead does 4 times as much damage as a 100mm warhead.  Said differently, he makes the claim that, yes, bore size has a linear relationship with damage.  Four times the size, four times the damage.

But that's just Mark Gellis. What does he know?  Does this bear out with the weapons in Ultra-Tech? Well, if we do a "like to like" comparison, we find that the Holdout Pistol and the Medium Pistol both seem to do roughly half the damage of the Magnum pistol which has twice their boresize.  Similar, the Anti-Material Rifle has a bit more than twice the boresize of the Hunting Rifle and does about twice as much damage.  There are some inconsistencies here: the assault carbine does less damage than we might expect, but it does less than the Hunting Rifle too, which is the same bore size.  The Payload Rifle does less damage than the Anti-Materiel Rifle, despite having a larger bore size.  But, we have some pretty solid consistencies too, such as the Machine Pistol, which has identical range and damage to the Heavy pistol and both share the same bore-size, suggesting that the Machine Pistol is just a heavy pistol with an automatic firing loader.  So I think we can chalk the inconsistencies up to other variables (different barrel length, weapon power, etc).  It passes the smell test.

Barrel Length

This is a hard one for me to measure.  I don't see much discussion in alternate design articles about barrel length (I tend to see more discussion about gun weight), but it clearly matters on some level.  A 10mm pistol does less damage than a 10mm Storm Carbine, which does less damage than a 10mm Storm Rifle, so clearly barrel length or something like it has some relationship with damage.  You can also see that as bulk rises, so too does damage, with some exceptions like the Payload Rifle.

Are the values in Vehicle correct? I have no idea!  But we can start with them, see if they pan out.

Ammunition Power

This seems to be a catch-all for how much powder is in a cartridge and how powerful it is.  I suspect it's also in play.  It might explain the Payload Rifle's miserable attack values (likely a low-powered weapon), but more than that, when we look at the rules for Liquid-Propellant slugthrowers, we explicitly see values for "boosted-velocity" rounds (1.3x damage), and "low-velocity" rounds (0.5x damage); the latter precisely matches the value for the "low-power" round, so much so that it looks pretty dead on.  So, for now, we'll assume that power factors in, and we'll use the "chunky" rules presented here, rather than finer grain rules on "grains of powder" that I've seen in some other systems.

Technological Factor

Surely, TL 9+ firearms are more efficient than TL 8- weapons?  Vehicles argues that guns to get more efficient with technological advances, but stops at TL 6. If so, then our weapons should just line up perfectly and, if so, then the problem with beam weapons and slug throwers is presumably present even if you throw UT weapons out the window and use HT guns.  For now, let's assume this is true and see if it pans out.  If we see that we're consistently "low" on damage, we can give our weapons an across-the-board buff.

Vehicles 3e vs Ultra-Tech 4e, a comparison

So the easiest way to resolve this is to simply design our guns based on our assumptions and see what pans out.

10mm Weapons

I started with the Heavy Pistol, and if you assume an "extremely short barrel," which is shorter than what Vehicles recommends for a typical pistol, you come to exactly... 3 dice of damage, which is exactly what Ultra-Tech predicts. This might be "too short," and perhaps a "short" barrel should have the modifier for an extremely short barrel, but it's at least consistent.  The 10mm Machine Pistol has exactly the same damage as a machine pistol!  If we assume a "medium" barrel (typical for carbines) on the Storm Carbine, we come to 7.5 dice, which is within spitting distance of the 7d given.  If we assume the Storm Rifle has a long barrel (typical of a rifle) we come to 9d damage, which is exactly right.

I found this line-up rather freaky. It suggests that the formula in Vehicles is exactly correct, and we can use it out of the box, at least for damage. It also suggests we don't need a "boost" for tech advances, which means that UT weapons are... just guns.

15mm Weapons

But who wants to mess with heavy pistols when we can play with magnum pistols! If we assume an extremely short barrel (again), we come to... 4.5 dice, while the reality is 4d+1, or about 4.3 dice, so it's quite close.  If we assume a Very Long barrel on the Anti-materiel rifle, we come to 15.75 dice, which is close to the 15d (perhaps rounded?).

So, once again, our weapons line up pretty well with the Vehicles formula.

7 to 7.5mm Weapons

These should be half as effective as the 15mm weapons, all things being equal, and that's what we see with the Medium Pistol: assuming an extremely short barrel, we get 2.25 damage, which is exactly half of the 4.5 for the Magnum pistol.  The Medium Pistol actually does 2d+2 damage... were the numbers massaged upwards to make it more palatable?  The Holdout Pistol, if we assume an extremely short barrel comes to... 2.25 damage as well. In short, it should do as much damage as the medium pistol, but it only does 2d damage.  It might be that Pulver "massaged" one up and the other down.  If we assume that the Medium Pistol had a "very short" rather than "extremely short" barrel, we come to 3.4 damage, or 3d+1, which clearly isn't right.

The assault carbine and the hunting rifle aren't exactly 7.5mm, but close enough at 7mm.  If we assume the Hunting Rifle has a long barrel (typical of a rifle), we get 6.3 damage, or 6d+1, which is exactly what we get from the statline, so looking good.  If we assume the assault carbine has a medium barrel, typical of a carbine, we get... 5.25 damage, or about 5d+1, when we expect 6d.  Huh?

This makes sense if you just look at the numbers on the page: they both have the same bore size, and the hunting rifle is Bulk -5 while the Assault Carbine is Bulk -4, so the Assault Carbine must be shorter than the Hunting rifle, though it should be noted that the Assault Carbine is much heavier than the Hunting Rifle (8 lbs vs 6.7), though that might be a factor of the loader (the Machine Pistol is an "automatic" heavy pistol and weighs 0.5 lbs more with no other differences, thus we expect autoloaders to be heavier than semi-automatic loaders).  So if we follow the numbers, the Assault Carbine should do less damage than the Hunting Rifle, and it does.. but only 1 point, not a whole die less.  So what's the difference?  A high powered round?

This is where we start to find some trouble with our formula and our numbers, but if we assume a little massaging, then things work out okay.

5.7mm Weapons

This gets a bit weird.

First, we have the PDW. If we assume a short barrel (typical of submachine guns) we get 3.4 damage, or about 3d+1, which is less than the 4d UT lists. If we assume a carbine-length barrel, we get 4.3, or 4d+1, which is too high. If we look at the bulk, we see that it's longer than the machine pistol but shorter than most carbines, suggesting that it's not a medium weapon, putting "short" at a good length.  Perhaps it's massaged?

But the Gatling Carbine doesn't help us either.  If we assume a medium barrel, we get 5.6 damage, or 5d+2, which is far higher than the 4d we actually see... which is an interesting value. It's exactly what the PDW has, damage-wise, and they have the same range, which suggests that they have the same barrel length, whatever it is, and the difference is that the Gatling Carbine is, you know, a gatling weapon and thus has twice as much mass as the PDW, which.. it almost exactly does!  So perhaps it has a Short barrel but its higher bulk comes from the gatling auto-loader, which makes it a more massive weapon.

25mm Weapons

Ah, the payload rifle.  We know its diameter (25mm), and we can guess at its barrel length: it's either vLong, like the Antimaterial Carbine (they have the same bulk), or Long, like a "rifle," and the extra bulk comes from the fact that it's just so big.  But if we assume the former, we come to 26.25 damage, or about 6dx4, a far cry from "10d." If we pick a long barrel, we get a more reasonable 22.5 damage, which is about halfway between 6dx4 and 6dx3 (3dx7?).  Again, too much for our 10d.  But if we assume it's "Low Velocity" already and inflicts halved damage, we get 11d, which we could massage down to 10d (or up to 12d, if we were so inclined).

What about the other guns?

There's a whole other page, plus various other small-arms found in More Ultra-Tech guns.  Why not look at them?  Well, I prefer to build a model and then use the remaining data to test it and I think we can already draw some conclusions from what we see here.

Conclusions

For damage, at least, it looks like the Vehicles values are pretty close!  We have a few that are off, like the Assault Carbine and the Gatling Carbine, while other sets that are so dead on it's amazing.  I'm inclined to believe that this formula, at least, is correct, and that the abberations are the result of massages and rounding to useful values, rather than some hidden variables I am yet unaware of.