The Reloading Press was a feature that ran steady for a while here on GB, but I lost track of it when I got busy publishing. But recently, I’ve been hearing noises about a new “best cartridge ever.” Well, that’s what nearly all new cartridge promise. Even so, this one was very interesting, and it combines two features I like – and that GURPS likes – in one place. A long, narrow, high sectional density bullet, plus a shorter, fatter case which gives a nice starting volume to keep pressure high.

.224 Valkyrie (5.7x41mm)

The .224 Valkyrie takes the basic case in one of my favorite cartridges for GURPS (and not bad in real life, too), the 6.8x43mm SPC, and then launches a long, narrow bullet from it with the same barrel diameter as the base .223/5.56x45mm NATO bullet.

It was developed in 2017, and really looks an awful lot like someone was playing with the GURPS ballistics calculator I developed. They weren’t, of course, but . . . well, see for yourself.

The basic concept takes a normal 6.8SPC case and launches a very heavy, long .223 bullet out of it. The standard load is 90 grains, whereas a usual match-grade or longer range .223 is 69 to 77 grains (depending on manufacturer). So this is going to be a bullet that really wants to not slow down . . . and you bet, one of the intended uses for the .224 Valkyrie is to ring bells to 1,000m while still remaining supersonic, which is about 350m/s.

The usual contender, the 62gr M855, or the improved Mk318 or M855A1, fall to the speed of sound at about 570m using my calculator, which says “accurate to 500-600m” out of the shorter barrel weapons that’s their design platform, and about 630m out of a 20″ barrel.

So what happens when you fling a 90 grain bullet out of a 20″ barrel? Nice things.

Ballistic’s Calculator Inputs

Basic inputs for the calculator are as follows, selecting 406mm for the barrel length.

.224 Valkyrie
Chamber Pressure 55000 psi
Barrel bore 5.7 mm
Case Length 41 mm
Chamber Bore 10.7 mm
Barrel length 508 mm
Bullet Mass 90 grains
Aspect Ratio 5.4 L/Bore
Burn length 14.66 mm
Projectile Caliber 5.7 mm
Total Accelerated Mass 90 grains
Expansion Ratio 2 expansion
Projectile Load 1


Output Stats
The rifle develops appreciable damage at pistol-length barrels, at least within the assumptions of the calculator. Why you would want to do this is another question, and putting all of that powder out of a 5″ (127mm) barrel is an exercise in gratuitous fireball generation (OK, maybe that’s why you’d want to do it).
At longer barrels – which is the entire point of the round – it comes into its own. Out of a 14.5mm carbine barrel, it’s still going to hit for 5d or 5d+1 and stay supersonic to 750m. With a target rifle of 20 to 24″, the calculator suggests nearly 6d penetration and an accurate range pushing 850m…and it will tumble and fragment (and not drop down to pi- instead of pi) to 220m out of a carbine and 320m out of a rifle-length platform. And that’s no joke.
Real-world data, rather than my calculator, pushes that supersonic distance to something like 1,250m with the right barrel and bullet. This thing can reach a long, long way. (Max range, not shown, is probably 4,550m with my calculator.).
So, here’s the chart:
Half-Damage Range 661
AP Wound Channel 0.5
Normal Channel 1.4
Barrel Length(mm) Barrel Length (in) Velocity (m/s) Muzzle Energy (J) Damage D&D Damage Supersonic (m) Pi to pi- (m)
117 4.6 475 658 3d+1 16 303 0
137 5.4 516 777 3d+2 17 385 0
160 6.3 555 899 3d+3 17 458 0
174.5 6.9 577 971 4d 17 496 0
204 8.0 615 1104 4d+1 17 559 25
241 9.5 655 1251 4d+2 18 622 87
285 11.2 694 1406 4d+3 18 680 145
311 12.2 714 1488 5d 18 708 173
364 14.3 750 1640 5d+1 18 756 221
442 17.4 793 1834 5d+2 19 811 277
524 20.6 830 2007 5d+3 19 856 321
577 22.7 850 2107 6d 19 880 345
700 27.6 890 2311 6d+1 19 926 391
  • The velocity is at the muzzle. The velocity with a 20″ barrel is tuned to match real-world data at 2700 fps, which is the long, heavy bullet designed to carry farther, rather than develop the most energy at the muzzle.
  • The pi to pi- range is where the damage drops from piercing to small piercing. For very short barrels (smaller than 177mm in my model), the bullet is slow enough that it will not yaw and fragment, and so it’s only good for pi- rather than pi. This is defined as 600m/s in my model, which is somewhat arbitrary.
  • It’s possible that the damage (penetration, really) is perhaps 10% high. That would still give a 20″ barrel about 5d+2, and a 14.5″ barrel a full 5d out of an M4 platform.
At any useful barrel length for a rifle cartridge, that is, about 9″ and higher (and that’s a darn short rifle), there is some range at which it will do its full pi damage type. At carbine length and above (14.5″) this is measured in hundreds of meters; this is a good choice at moderate range as well as long.
For GURPS gunners, it’s a good cartridge, though not a great one, I think. The long range is short-changed in the calculator vs reality, and the difference between (say) a 320m range where it drops to pi- and a 660m 1/2D range is pretty far beyond the usual engagement distances for PCs. You do get rifle-size penetration out of a carbine-sized platform, though, which is nice. I suspect recoil is manageable as well.
Where this will do well is if you don’t want to lug around an 9-11 lb rifle in the form of a .308, which has a lower tumble range (250m) and a lower 1/2D range (575m) than the 320m and 660m of the .224 Valkyrie. If the 7.62 actually drops from pi to pi- when it drops below 600m/s or so, then there’s a weird case where at 250-350m, and then between 575 and 660m you’re better off with the .224 Valkyrie, but at other ranges you’re better off injury-wise with the .308. That’s cutting it pretty fine: what in general this means is that with a full-length rifle in both cases, you can go with a lighter platform (AR15 rather than FN-FAL, AR-10 based). That can save you three to five pounds on your arms. Also, the ammunition is lighter and the magazines bigger for the .224 Valkyrie.
For GURPS, though, you really need to care about reaching out a long, long way with a lightweight weapon before this becomes something you’re looking at seriously. Ironically, where the 6.8SPC got somewhat of a “meh” reaction in the real world, in GURPS it’s like the .40S&W – a goldilocks cartridge where everything is “just right.” At 6d it’ll drop Joe Average to -HP in one shot, and 3d to the vitals at distance is still a potential lethal dose through light body armor.
You need a purpose-built upper receiver (or at least a barrel, chamber, and bolt change) to shoot this cartridge. The thing is going to look like every other AR-15 style rifle out there on the outside, and you’ll spend (in 2019) anywhere from $350 to 700 to get one…unless for whatever reason you want/need to spend more (for things like super-custom, which is frequently a great excuse to buy Weapon Bond).
So no real details or special platform list today! This modification gives you a bit more penetration, a bit more range, and a bit heavier ammunition out of a barrel that’s the same bore as a standard M16/AR15. It does this by increasing the size of the cartridge case, which keeps the pressure higher as the bullet goes down the barrel, and by shooting a round that’s probably going to be 50% heavier than the one you launch out of your standard M16 type platform. For carbine users, this is a good thing, in a way, because it retains its full damage 50% farther than the lighter round (though both have roughly the same 220m or so range to where they both drop to pi- from pi).

Over the past, in various GunDay posts, I’ve taken a look at the various Ultra-Tech weapons with a mind to both determining the feasibility of the weapons, and also checking their performance.

One of the more interesting posts, to me at least, was a ground-up redesign of a service pistol. The “ideal” pistol seemed to fire a 5.9mm projectile of unique engineered construction, which basically fired an advanced projectile that combined the AP capabilities of a tungsten tip along with a base that the tip gets pushed in to, which expands like the petals of the Ranger SXT modern-day JHP in order to enlarge the wound channel of the projectile to greater than 10mm, the threshold for pi+.

That gave us a projectile that wound up doing 2d (2) pi+, which wounds like a .45ACP and penetrates like a carbine, with a 20-round capacity that disappeared into a standard pistol grip.

Along the way, I also took a look at the Liquid Propellant (LP), Electrothermal-Chemical (ETC), and Electrothermal-Kinetic versions of various rifles, and found out (honestly, to my surprise) that all three were feasible with the right assumptions.

This particular article will take from all of those technologies in order to come up with a competitive TL9 rifle that’s an actual upgrade over TL8, and puts the right amount of power into the hands of the standard infantryman. Continue reading “Ultra-Tech Rifle: From the ground up”

When Shawn Fisher emailed me that the US Army was looking at adopting a new medium machinegun, this one capable of accurate automatic fire at a range of over a mile, where the M-2 in .50BMG can only deliver single shots, I was intrigued. When I heard it was being considered in .338 Norma Magnum, I knew it was time for a reloading press.

The case and length were designed purposefully to launch the 300-grain, 8.6mm Sierra MatchKing bullet. It’s a long projectile, with an aproximate aspect ratio of 5.6 (compare the 5.56, 7.62, and 12.7mm standard projectiles at about 4:1). This will provide outstanding velocity retention and penetration with distance. The projectile length is an artifact – or more properly – a design intent, of the cartridge and projectile’s intended use: long-range precision marksmanship. Continue reading “Reloading Press: .338 Norma Magnum”

A brief digression into advanced conventional gun technology in GURPS Ultra-Tech.

There are two advanced technologies for firearms in GURPS Ultra-Tech. Liquid Propellant slugthrowers improves piercing damage by +1 per die (about 28%) with the boosted velocity version, and there’s a low velocity option that cuts damage in half, but we don’t care that much about that. Electrothermal-Chemical weapons increase damage by 1.5x. There are also Electothermal-Kinetic weapons, discussed in a Designer’s Notes for Ultra-Tech, Fourth Edition article, which are even more badass, multiplying damage by 2x.

What does that mean in terms of weapon design?

The Ballistics Model

My model – and remember, all models are wrong, some are useful – takes the peak pressure and maintains it for a certain distance down the barrel. This adds Pressure x Barrel Bore Diameter x Burn Distance in energy to the bullet: a straight-up application of energy equals force times distance. After that, it assumes that the propellant is all burned, and that the chamber and barrel and bullet form a pressure vessel, with the instantaneous pressure calculated using the ideal gas law. One can then calculate the instantaneous force at a given length down the barrel, and sum the product of that force over the distance – you’re performing an integration: E = Integral of F dx.

That’s wrong.

It just is. It’s not unusable, but it’s a simplification. It neglects the non-ideal component of the pressure equation, and it really ignores the fact that as the bullet is driven down the barrel, there is an opposing force of friction acting to retard the projectile. So while in real life, there’s an optimal barrel length after which more barrel is a hindrance to velocity, my model assumes that the bullet will continue to be accelerated pretty much forever.

That it falls off over distance, though, means that you need more and more barrel to actually get a GURPS-useful boost in velocity. So in practice, while it’s “wrong,” it’s not so wrong by so much that it doesn’t provide a useful and self-consistent model. Perfect? No. Usable? Yah.

But given the way that the program works, there are really only a few ways to add energy to the projectile. Continue reading “Ultra-Tech Firearms: Liquid Propellant and ETC”

In the last installment, a few of the basic weapons from the Rifles section of GURPS Ultra-Tech were examined. The basic premise was to see if the designed stats make sense, and evaluate them against an assumed mission statement: deliver 3d-6d injury after penetrating whatever armor the target is wearing. The typical foe was assumed to be a TL8 trooper wearing roughly DR 35/10d worth of hard/soft armor combination. This might be the TL8 Assault Vest + Trauma Plates (DR 12/5 + 23) or Advanced Body Armor (the generic form of DragonSkin, assumed to be as effective as the manufacturer claims).

Last time, we covered the basic Assault Rifle, and a derived hunting rifle firing the same ammo, the gatling carbine, and the 15mm payload rifle.

Today we finish up with some oddities, large-caliber specialty weapons that are either overdesigned or mis-applied in many cases. Continue reading “Gunday Continued: Ultra-Tech Rifles (Part 2)”

The Reloading Press is an approximately fortnightly (every other week) feature here on Gaming Ballistic that started in 2016. Each article looks at some interesting real-world cartridges and presents them with hopefully-useful information in GURPS format. Except when it’s interrupted by massive writing projects, something interesting should appear every couple of weeks.

6x35mm KAC

The 6x35mm KAC seems to be another reaction to the desire to give folks a short, handy shoulder arm that hits harder than a pistol against what I’ll call “firm” targets. They’re not “soft” targets (unarmored folks in light clothing), nor are they armored behind real cover or wearing Class III or IV level protection. They’ve got soft body armor or clothing thick enough to pose an issue against handguns, or are behind fragile but hard window glass that provides a measure of barrier protection, if a permeable kind.

There’s a lot of information about this round that seems to be classified. It was designed, seemingly, because when you take a round designed to perform well out of a 500mm barrel (the 5.56x45mm) and then chop said barrel down to 200mm, surprise-surprise you get issues. Low muzzle velocity and a fireball and concussion that likely rivals Thor getting frisky with Mjolnir.

So Knight’s Armaments Corp was contracted (or just decided and then got a contract, but I think the design was solicited) to do essentially what I did with the ultra-tech bullet design: take the bullet and the gun and design it all to a purpose: fire something fairly lethal out of a very short rifle. Continue reading “Reloading Press: 6x35mm KAC (many guesses)”

Idle conversation on the Discord chat about a full-auto .50 BMG rifle (as opposed to a machinegun) led to the comment that for sufficiently strong and large races or creatures, they really should be kitted out with battle rifles in sufficiently impressive calibers.

I mean, why wouldn’t a large-enough race make a rifle capable of firing 14.5mm KPV rounds?

Now, it’s been a while, but I don’t think a character’s ST has any impact on a weapon’s stat line.

Let’s look into fixing that. Continue reading “Rcl and ST in GURPS”

Continuing with my exploration of redesigns of the slugthrowers presented in GURPS Ultra-Tech, the next step is to look at submachine guns (SMGs), and Ultra-Tech (sensibly) includes Personal Defense Weapons (PDWs) in this category. However, if one looks at my prior articles, a raw-stats look at the four Ultra-Tech pistols, as well as some heavy design and less-heavy mechanics look at a ground-up TL9 pistol concept, you can see there’s already been some groundwork laid that should influence the following examination.

Prior Art

What concepts have been introduced?

  • TL9 10mm ammo has a base damage of 3d+2 pi+ out of a 4.5″/115mm and delivers around 1,100J of energy
  • There is a family of combustible case 7.8mm ammunition that deliberately targets GURPS breakpoints to deliver 2d+1 pi damage from an 85mm barrel, and 2d+2 pi from a 145mm barrel as a service pistol
  • An integral suppression system probably weighs about 0.1 lbs per 50mm of barrel
  • There’s a high-tech ammo type that was shown as an example of a TL9 combustible case or caseless telescoped cartridge. It uses a long bullet that expands to 75% of the length of the bullet in diameter. Call this CCTAPX (see-tap-ex) for combustible-case telescoped expanding. It’s cost per shot, though, is probalby 10x normal.

What is an SMG/PDW, anyway?

Ultra-Tech uses a fairly conventional classification of weapons, putting SMGs (which it defines as 10mm full-bore pistol rounds from a rifle-shaped platform) and PDWs in one group . . . but classifying short-barreled rifles, the carbine family, along with rifles. Continue reading “GunDay: GURPS Ultra-Tech SMGs and PDWs”

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. Continue reading “The TL9 Pistol – Design Directions (GURPS)”

GURPS Ultra-Tech is a nifty book full of some fine inspiration. It is, however, a victim of being one of the first Tech books out there from fourth edition, and one that tried to be a few things at once, possibly while it was being written, possibly during playtest, and certainly during the post-playtest rewrites that occurred.

The projectile weapons are . . . in need of some work. There are some notable issues for the weapons, and honestly what they’re in need of is a redesign, rather than a rationalization. So, without further ado, here are some thoughts.

I’ll redesign each of the four TL9 pistols in the book, trying to keep close to as many of the stats as possible, but changing the ones that make no sense. Continue reading “Sunday is GunDay: GURPS Ultra-Tech Pistols”