The TL9 Pistol – Design Directions (GURPS)

There’s an interesting problem – or at least an observation – when looking at the near-future slugthrowers from GURPS Ultra-Tech. The weapons themselves are a mixed bag of “well, it must be better!” and “there’s hardly any way that can happen.” It’s understandable, but leaving that aside, a futuristic pistol is a problem no matter how you slice it.

Why? The presumption of evolving threats, and a natural asymptote in the evolution of a design that debuted, fundamentally, in around 1900. The broom-handle Mauser C96, the M1900 Browning, and of course the M1911 Colt .45 ACP are all basically TL6 designs that evolved through two tech levels (in GURPS terms) to arrive at the early 21st century darn near as improved as they’re going to get.


One of the things one has to realize about a pistol is that they’ve always been secondary weapons. They were a one-shot (or even six-shot, in the US Civil War) first-strike to be wielded along side a saber, the primary weapon, initially. Then they were an officer’s weapon or signature, carried by commanders partially in order to remind them that their role was to direct troops, not engage in personal heroics.

Side note: I’m not necessarily making that up. I knew, personally, a Navy SEAL commander who was in Viet Nam. He was the course leader for the McKinsey and Company “mini-MBA,” and a great guy. He was quirky – he went swimming five times a day – but he told great stories, and his charisma and leadership were palpable. Naturally, I engaged him in conversation, and he told me that he rarely (maybe not ever) carried a weapon larger than a pistol, for that exact reason. His troops were there to kill the enemy; he was there to direct his troops. Staring over a gunsight robbed him of strategic vision. Hrm, says I.

But the thing about a pistol is that it’s not a primary weapon. As the old joke goes, “if I were expecting trouble, I’d have brought my rifle.” It’s a defensive or backup weapon that you can have with you all the time. While there’s no question a pistol can seriously kill you, it’s not a “serious” weapon for offensive purposes in nearly any case [1].

So we need to define what the mission of the weapon is. And I’m going to be pretty restrictive about it.

  1. It needs to be something you can carry with you at all times, comfortably. This probably limits total weight and size
  2. In many cases, it needs to be something small enough to carry concealed at all times, and be comfortable doing so
  3. It needs to pose a credible threat to an unarmored person
  4. It needs to be accurate and controllable enough to be used in two or three round salvos; if it’s worth shooting, it’s worth shooting twice
  5. It should hold as many bullets as possible without violating rules 1-4

Note how I don’t say “it should penetrate body armor.” Punching through armor is an offensive task. If you really want to stretch it, you can say that it should potentially be able to incapacitate someone through light armor, and by light we’re probably talking about car doors or casual protection – probably no more than DR 8, maybe even as low as DR 4. If the threat is wearing more than that, you need a rifle.

What does “incapacitate” mean? Heck, it probably means a single vitals hit will make you start rolling for unconsciousness. That’s an average penetrating damage of about 1d+1 pi. Asking a “casual” hit to the torso to do that will put the requirement of base damage in the 3d to 3d+2 range . . . which is 10.5 to 12.5 points of damage. With a pi+ bullet, that’s 2d or 2d+1.

That’s a reasonable ask in either case.

Ammunition Concerns

Both in GURPS and in real life, the trade-off between bullet size and marginal injury improvement and number of rounds carried and shootability is real. If you fire 10-13mm bullets, you’re into GURPS’ pi+ category, which is great . . . but those bullets tend to be 165-250 grains (10.7 to 16.2 grams; the NATO 9mm is an 8g bullet) and the sheer diameter of them makes for ergonomics and weight issues. A double-stack .45ACP like the Glock 21 or a 10mm Auto like the Glock 20 is a positive handful. Single-stacks (the bullets in one column rather than two) are much more easily gripped, but obviously run into an issue of having roughly half the capacity. Consider that the 9mm Glock 17 holds 17 bullets and is gripped easily by just about anyone, while the Glock 21 holds 13 and is beefy, while the M1991A1 in .45ACP in single-stack configuration is usually a magazine capacity of 7-8. Ramping down even further, the 5.7x28mm Five-seven pistol holds 20 . . . but the cartridge length of about 41mm, rather than its width of only 7.9mm, makes this a handful as well, and the fact that the projectiles are only 2g rather than 8g or even 15g has raised performance concerns with respect to wound channel. Using my ballistics model, even giving it full credit for moving sideways (which it reliably does in gelatin), the wound channel modifier is about 0.7, not enough to eke up to full pi, but about as good as the 7.8mm projectile posited in the post on TL9 pistols. So from that perspective, the very small, designed-tumble rounds are about the equivalent in wounding as our small-scale 7.5-8mm bullets, but the 7.8mm is good in GURPS because it deliberately targets a stat breakpoint between pi- and pi. The very, very lightweight bullets also have poor sectional density due to construction, though they try to make up for this with velocity and construction.

In any case, for a future bullet we can techno-magically relax some of the constraints.

Improvement Vectors

So enough history and preamble. If we’re going to make a TL9 pistol, what are the opportunities for improvement? There are really only a few directions we can go:

Projectiles. We can see how many of the properties of good penetration, good capacity, and good wounding we can get into a bullet. There are likely diminishing returns, but with caseless ammunition and a few hand-waves, we might be able to do something here. Especially if price is no object. The penetration can be improved through hardness, shape, and velocity; the first two are achieved by projectile construction, the last by pressure and barrel length, that is, weapon construction.

Weapon. This is where some of the improvements can come. Stronger materials will support a higher pressure in the chamber, which will give higher velocity and higher recoil impulse. The GURPS damage model is basically linear in velocity, so one gives the other. Improved accuracy might be had, but short barrels will limit this. Today’s pistols are going to be somewhere between Acc 2 (a 4.5″ group at 25 yds) and Acc 3 (a 1.8″ group at 25 yds). While delivering Acc 4, a 0.9″ group at 25 yards might be notionally possible, it’s probably not practical – combat shooting doesn’t need to be quite that precise. So Acc 3 is probably reasonable and expected for service-size pistols.

Range? Eh. Nearly any pistol will be used well within its half-damage range nearly 100% of the time. It’s basically a non-issue.

Weight should be kept to about 2 lbs for a service pistol, and 1 to 1.5 lbs for a concealed one (a “holdout” pistol in GURPS terms). The thinner the cartridge, the thinner the weapon can be, which allows it to be concealed without “printing” clothing more easily. Practical pistols of either the holdout or service variety are going to be Bulk -1 or -2, so no point in designing around that. Shots should be kept as high as possible, while Rcl should be managed to Rcl 2 to enhance multiple-hit possibilities in rapid fire (which will be RoF 3 due to semi-auto rules).

That gives us pretty much the ideal stat line for a weapon. We’ll return to it in a moment.

Accessories. Lasers, reflex sights, computerized aiming aids – all add to Guns skill rather than Accuracy, and so are even better than precision from the perspective of the user. If a true reflex sight with its +1 to Guns (Pistol) could be integrated, somehow, into a profile no larger than modern tactical sights through miaturization, holographic doo-dads, or handwavium that would be ideal.

The other two places where you could really help is in sound suppression – pistols are loud, and even more so in confined spaces, and recoil management. Compensation systems might take a very large round and tame it to keep it Rcl 2. I suspect that the slow-down in gas velocity required to achieve suppression is antithetical to the sharp control venting required for muzzle management. I will, for reasons to be explained, choose integral suppression, using magical lightweight materials to keep the overall weight of the weapon unchanged.

Ideal Future Ammo

Ultimately we want to have it all. An armor piercing bullet with good expansion and wound profile. Something like 2d+1 (2) pi+ would be really, really sweet. But can we get there? If you’ll allow me to pull stuff out of my butt for a bit. . . perhaps.

Let’s start with some constraints. I’d like a cartridge that’s no longer than a 9mm or a .40S&W, because those are comfortable grips even for those with small hands. That limits our length to about 30mm. Still, that’s not bad. Let’s also start with our 7.8 or 7.9mm cartridge width, calculated from the last post.

Here’s where we’ll deviate from conventional wisdom. What we’ll do is look at a rifle-profile bullet, in a caseless/combustible case telescoped cartridge.  We leave 1mm on each side to wrap the projectile, and 7mm at the base. This gives a projectile with diameter of 5.9mm and a length of 21mm, and that’s a length to width ratio of about 3.56. It’s not quite as long and skinny as a rifle round (which will tend to the 4-5 range), but it will have reasonable mass . . . especially after we get finished with it.

The ogive-ish part of the bullet is 1/3 of the volume; the solid-ish cylinder is 2/3 of the volume. That’s 144 and 287 cubic millimeters each. Why does this matter? We’re going to make the top of the bullet a hardened penetrator, made of tungsten, for 2.78 grams. We’ll make the back end of the bullet jacketed lead or maybe perhaps something exotic like a 50-50 copper-tungsten metal-matrix composite, which is machineable and somewhat soft because of the copper, but has a density of a bit more than lead, which is desirable for mass. That gives a bullet base of 3.4g, for a total projectile mass of 6.2g, or 95 grains, comprised of 2.78 grams of penetrator, and 3.4 grams of “base.”

That gives 1040 cubic millimeters, or about 1 cubic centimeter, for propellant, primer, and stabilizers. Modern smokeless powder has densities between 6 and 15 grains per cubic centimeter; a 9mm pistol might only fill with 6 grains of powder anyway. Maybe less. So we can have a more powerful “Plastex B” type of propellant and most of that cartridge volume is stabilizers or rigidity enhancers.

So this is mostly viable construction, and we can easily generate pressures from a 9mm-like 35,000psi to probably double that, but we can cap it at a magnum rifle-like 62,000 psi. Point here is that we won’t be constrained for oomph.

So that’s all well and good, but how do we get the cross-section up? We’re going to wave our hands and say that the penetrating tip compresses into the base and expands it like a hollow-point bullet, opening like a flower petal (or more precisely, the Ranger SXT) at the base to provide a better wound channel. How much better? Probably in the neighborhood of 14-15mm. The conceit here is that the hard projectile would punch through armor, delayed just long enough to push the “petals” out of the base, which is softer and would provide the wounding.

When I do the math on this, I’ll treat it as a full-weight projectile for armor piercing capabilities, but for wound channel, I’ll only give “credit” for the 52.5 grain base. Note that this is very nearly the mass

Ranger SXT – Design Inspiration

of the old M193 5.56x45mm round, so with good expansion and sufficient velocity, this is not crazy-town from the perspective of wounding. The light residual projectile should be offset by a very large frontal cross section. Plus, the 43-grain tungsten penetrator is, by itself, heavier than the entire projectile of the SS190 that is the 5.7x28mm.

So . . . can we get there? Turns out that the wound channel modifier of this lightweight but highly expanding base is about 1.6 . . . so pi+, meeting our design requirement for wounding.

The precise characteristics – meaning damage and range, will depend on the weapon itself.


We’ll start by designing a TL9 service pistol. As noted, we’ll make it double-stack capable, and it’ll hold about 20 rounds in a conventional-sized magazine. We’re going to want to give it as good a chance to eke out velocity as possible, and we’re dealing with a profile roughly the size of the Five-seven in terms of projectile and weapon – but we can take advantage of the Boberg/Bond Arms bullpup design to help here. The Boberg/Bond XR9-L puts a 4″ barrel in a 6″ gun; the FN Five-seven is 8″ long, and the Walther PPQ is 7.1″ long, so an equivalent service pistol with a 7.5″ length can have a 5.5″ barrel, or 140mm.

That sets the parameters of the barrel and chamber: 7.9x30mm chamber, 5.9mm diameter barrel that is 140mm long.

If we give ourselves the same chamber pressure as a 10mmAuto (37,500psi), pushing a 95-grain projectile, we get a fairly respectable 400m/s velocity, just shy of 500J, and 2d+2 base penetration.

If we only give credit for the hard penetrator (43 grains), the penetration is 1d+3, or 6.5 points. At 400m/s, the base clocks in at 2d pi+

So if all goes to plan, what we have here at the low end is something like 1d+3 (2) pi+, and at the high end it’s 2d+2 (2) pi+.

In the end, I’ll split the difference for simplicity: call it 2d (2) pi+.

The overall weapon will likely weight about as much as the five-seven pistol, at 1.3 lbs empty. Hey! That gives us some room – a pistol suppressor from GemTech for the five-seven is only about 0.33 lbs, so we’ll give the benefit for a 10% weight reduction, and call the suppressed pistol, unloaded, at 1.6 lbs. Add an empty weight of 0.2-lbs. for the magazine, a weight-per-shot of 110grains, and the loaded weapon is 1.95 lbs, and each spare magazine is 0.35 lbs.

TL Weapon Damage Acc Range Weight RoF Shots ST Bulk Rcl Cost LC WPS
9 Service Pistol, 5.9x30mm CTLA 2d (2) pi+ 2 575/3,200 1.95/.2 3 20 8 -2 2 $1000/35 3 0.015

Could we goose the Accuracy a bit? Likely, but that’ll cost ya: call it $1,500 for Acc 3.

Speaking of cost, the ammunition will not be cheap. Even assuming mass production, I’m assuming $5 per bullet for civilian sales, and maybe $2.50-3.00 each for boxes of 50 for law-enforcement types. Maybe if you’re in the military and buying millions of them, you can get it down to $1.00-1.50 per round. That makes an assumed cost on the order of $85-100 per full 20-round magazine including the actual empty mag.

Parting Shot

What we have here is a properly upgraded TL9 service pistol. It penetrates as well or better than nearly any full-caliber TL8 SMG (but not better than a full-sized carbine with a proper military cartridge), and delivers an equivalent wound to a .45ACP, which is capable of doing 21 HP of damage to the vitals, or 10-11 to the torso, on one hit.

Recoil compensation is probably not necessary (and with the integral suppression, probably not feasible). The overall momentum of the projectile is 20% less than the 9mm. Grip size will be manageable thanks to the telescoped cartridge, and the narrow base allows for sufficient magazine capacity to please nearly anyone. Integral suppression makes it friendly for use inside buildings or cars, though this is all relative: it’ll still be as loud as popping a balloon, or maybe dropping books on the floor. But it’s outside the “instant hearing damage” range, and maybe even outside the “onset of ringing ears” range, which is much better.

Good accessories here would include the integral laser sight, probably held within a guide rod, HUD compatibility. If we could magitech our way to an integral reflex sight that didn’t ruin the profile of the weapon (whether it’s a flip-up reflex that is somehow immune to damage, or some sort of projected dot that doesn’t require the large glass lens needed on current sights) that would give the +1 to Guns skill without giving away position like a laser would.

Against body armor, you can face down DR 7 and only lose the equivalent of 1d. That only gives you 1d pi+ after armor, but that’s 1-9 points per hit, so with two or three hits, the foe is still down, and 1d to the vitals is No Joke.

So I feel like if folks are willing to accept the considerable assumptions behind the design of the ammunition and weapon, we have a nice improvement on several avenues of performance.

Holdout Pistol

Heh. Forgot the holdout version. Chop the barrel length to 80mm, lose the suppressor to save bulk (and a suppressor that short won’t do much anyway). Single-stack magazine and careful construction probably gets the width of the weapon down to 0.7″.

TL Weapon Damage Acc Range Weight RoF Shots ST Bulk Rcl Cost LC WPS
9 Holdout Pistol, 5.9x30mm CTLA 1d+2 (2) pi+ 1 575/2,900 1.0/.2 3 10 8 -1 2 $600/35 3 0.015

[1] There are limited cases where this is not true, and those mostly involve things like tunnel clearing when the primary impediment to effective weapon use is its bulk, not its power. Even so, if you’re clearing a tunnel filled with Mobile Infantry troopers in power suits, well, a pistol short of some sort of magi-tech just won’t do it either. I did write about self-defense pistols impressive enough to act as a primary weapon in my post Self-Defense Weapons, though.

Precis – Following up on the TL9 pistol article prior in the week, what would real advancements in sidearms look like? Start with the ammo, then move to the platform itself. Let’s find out.

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