[Ultra Tech] Increased Firearm Power with TL

[Varyon]

David Pulver responded in my other thread, with some comments I felt were more appropriate for this one, so here we go.

Originally Posted by David L Pulver

Advanced chemical propellents certainly exist, but I do think that there is a tendency keep things fairly static rather than advancing them every TL; if people are conservative about guns they're even more so about propellants. One of the things I learned when researching weapon design systems is that most small arm cases are not as densely packed with propellant as they could be. (This is maybe 40-50% density for pistol ammunition, about maybe 80% density loading for rifle ammo and somewhat higher for high-velocity cannon ammo). But a lower density tends to improve reliability and reduces ammo cost (simpler tolerances etc). In general, you can more or less treat most TL6-8 propellants similar except in some very high-end examples. ETC technologies are actually often stated as helping better enable the transition to more advanced solid propellants, as they mitigate some of the issues encountered.

If the trend of rifle ammunition being ~80% filled continues, going above ~+10% to damage may not be feasible for such - but you could potentially have weapons designed to take cartridges that are normally filled to a lesser extent, to leave room for extra-spicy loads. If you have more powerful propellants as well, these might not be any larger than modern rifle cartridges. +10% damage would call for starting with around an 80% fill, +20% (TL 9) around a 70% fill, +30% (TL 10) around a 60% fill, +40% (TL 11) around a 50% fill, and +50% (TL 12) around a 45% fill, such that boosting to 100% fill would get you to the necessary energy level. This calls for around +14% energy density (compared to TL 8 propellant) at TL 9, +33% at TL 10, +60% at TL 11, and +78% at TL 12. Does that seem feasible? It's a bit more than x1.15 (compared to the prior TL) per +1 TL.

Originally Posted by David L Pulver

The general data I saw was that current R&D in the US aimed ultimately to increase muzzle energies by as much as 25% without increasing barrel wear through new technologies that reduced the heat of ignition, etc. Buzzwords were propellants based around thermoplastic elastomers (TPEs) using novel nanostructured energetic materials often in advanced layered geometries with outer layers of slow burning propellant and inner layers of fast-burning, thus producing sustained pressure curves similar to the advantage gained by ETC. It is also noted that ETC is synergistic with advanced propellants and by optimizing them you can get even better performance. A 25% objective increase in muzzle energy equates with about 10-11% increase in damage and both 1/2D and Max range, and about a 5% increase in ST and Rcl. numbers. The Rcl. mod is mostly invisible.
It remains to be seen whether this objective could be achieved without extra temperatures that cause barrel erosion.

I like the idea of having layers of propellant that burn in a specific order, although it seems like the necessary precision of manufacturing such could result in rather expensive ammunition. Maybe you could wind up with a choice between a more expensive ETC weapon or more expensive ammo that has the same effect in a normal firearm? Given the necessary ammunition cost of training, I would expect ETC weapons would be preferable...

Oh, and am I interpreting correctly that you can get the damage multiplier from the square root of the muzzle energy multiplier (1.25->1.12), and the MinST/Rcl multiplier from the square root of the damage multiplier (1.12->1.06)? Because that would be great information to have. What impact would weapon weight have here (the forgotten part of my original question - if you reduce the weight of the weapon by making it unable to handle more than +10% damage, how does MinST change)?

Originally Posted by David L Pulver

I'd probably say a more conservative TL9 is about x1.1 for advanced propellants alone, solid or liquid, or just assume they're the same value but a little less is used, and it's folded into the weight saving for caseless to get the "twice as many shots with caseless" simplification (it's probably closer to 1.7-1.8x as many shots otherwise). Then about 1.5-1.6x as effective energy with solid advanced propellant + ETC (or possibly with TL10 liquid propellant) which in game terms would simplify as about 1.25-1.3x muzzle velocity and damage, giving a nice "+1 per die" modifier. After that, I'd probably just say "go mass drivers" at 1.5 to 2x the muzzle velocity and 2-4x the energy, but you might shoehorn advanced liquid propellant + ETC into there somewhere in between, though skipping that entirely is also viable.

It might be interesting to posit continued advancement in propellant at each TL, but have mass drivers typically overtake them at TL 10 or so.

[Anthony]

Originally Posted by Pursuivant

Another possibility is not more or faster- or hotter-burning propellant, but more efficiently-burning propellant.

That is part of the real-world motivation for ETC ammunition -- spark ignition can give you better control than a primer.

[David L Pulver]

Originally Posted by Varyon

Oh, and am I interpreting correctly that you can get the damage multiplier from the square root of the muzzle energy multiplier (1.25->1.12), and the MinST/Rcl multiplier from the square root of the damage multiplier (1.12->1.06)? Because that would be great information to have. What impact would weapon weight have here (the forgotten part of my original question - if you reduce the weight of the weapon by making it unable to handle more than +10% damage, how does MinST change)?

Well, there is no official system for GURPS gun stats, so all I can say is how I do it -- you're free to make up your own numbers!

In my own draft system a small change won't make that much difference to ST. The damage is linear with muzzle velocity if caliber is unchanged, so that increasing muzzle velocity tends to increase the recoil stat in a small but linear fashion (it's small because Rcl is rounded to nearest whole numbers and then added to a flat base of 1 on top of that) while ST is a mix of weapon weight and felt recoil and due to the quadratic nature of 4e ST, the change is usually minor.

Often a significant reduction in weight while keeping damage/velocity the same will result in the weapon kicking about a lot more and thus harder to hit things with rapid fire (higher Rcl) but the ST not changing much (because you've made the weapon lighter, so it's easier for your ST to manage even if it does kick more.)

[David L Pulver]

Originally Posted by Pursuivant

Another possibility is not more or faster- or hotter-burning propellant, but more efficiently-burning propellant.

For example, modern "black powder" guns are more efficient than their TL4-5 predecessors because grains of black powder substitutes like Pyrodox are uniformly sized and are shaped for optimum combustion. T.

Indeed. Different TLs of "black powder" affect muzzle energy. (Even for smokeless powder, the stuff used in cannon is somewhat different than that used in small arms). Some propellants also burn differently. Black powder (and Pyrodox) actually have radically different pressure curves than smokeless powders, which significantly affect how barrel length affects muzzle energy and thus velocity. (This was giving me odd numbers for TL4-5 black powder propellant in my own conversion formula until I found an article that showed the difference, and let me incorporate those factors. But that's really only relevant when trying to work out how much velocity a given weight of powder generates for a given caliber in a given barrel; if you already know muzzle velocity or muzzle energy and caliber, you don't need to worry.)

[David L Pulver]

Originally Posted by Anthony

The SIG Fury did not raise muzzle velocity significantly. Raising muzzle velocity with +P ammunition and the like is really a pistols-only phenomenon.

Yeah. In my design rules, pistol ammo is generally low-powered, meaning it's loaded at somewhat under half the maximum volume capacity for a given size of case, so uprated ammo can be quite significant change. In rifle ammo (or autocannon, tank gun, etc.) ammo the casing is already very nearly full, so the performance gain of stuffing the casing even more full tends to be minor at best. In GURPS terms, it's usually not worth worrying about.

[David L Pulver]

To address the original point: certainly one can make a case that ammunition chemistry will get better and material strengths also improve, and so making a rule that this is what happens every TL is quite justifiable!

In general, I wouldn't put something like that in a core "Ultra-Tech" book because it's a pain to recalculate all the ancillary numbers, any more than I'd raise damage of swords and modify breakage risks by a few percents or pluses every TL after TL8 to account for similar gradual improvements in steel alloys.

In blades, I'd be inclined to offer one "advanced alloy" option and then add a bunch of radically new technologies every couple of TLs (or via superscience) with monoedge, vibro, hyperdense or whatever.

Likewise, in guns, to avoid having to create new weapon tables every TL for every darn weapon, I'd be inclined to just focus on a couple of incremental upgrades (liquid or ETC) and maybe a single advanced propellant option that is factored into the TL9 numbers, before things go all gauss-like at high TLs.

Again, this partly due to seeing how conservative regular firearm changes were at TL6-8 in terms of raw damage and range (unless the bullet is changed), at least in GURPS terms. But it's mainly due to being sufficiently lazy that I don't want to deal with creating whole new firearm stat blocks f or TL10, TL11, and TL12 versions of TL9 guns....

[Rupert]

Originally Posted by Fred Brackin

http://knowledgeglue.com/what-are-th...ers-in-the-us/

......seems to have .44 Magnum as the 15th most popular caliber in the US with 1.4% of the market. With 2018 numbers of 8.1 billion rounds sold in the US that should come to over 100 million rounds sold in one year.

That probably counts as significant to the ammo makers. Even some of those calibers you want to count as "zero" are probably significant.

That seems to be based on gun sales, not ammo sales. I expect that they won't be quite the same - if nothing else most people with .454 Casulls (#48) and the Weatherbys probably won't be putting that many rounds through them each year.

[Rupert]

Originally Posted by Varyon

Although maybe part of the necessary changes to get better performance is a heavier (and thus probably longer, given constant caliber) bullet, which may not feasibly fit in a typical cartridge?

A longer case, and/or overall cartridge length is not an issue in terms of the tech. It's a small issue when it comes to use (but really not one at all for battle rifles and machineguns). Mostly it's an issue with manufacture because it means all new receivers and bolts, etc., and the US arms industry is very heavily invested in standard M16 sized parts, and they don't have enough length for a longer (say .30-06 or 7.62x54mmR) cartridge.

There may be issues with exceeding certain speed limits, in which case you'd increase kinetic energy by using a heavier bullet instead.

Barrel wear is the big one, it it'll be worse when gaining your velocity through pressure rather than through long barrel length and slow-burning powders (the invention of which in the 50s and 60s had a lot to do with the proliferation of big magnum hunting rounds, BTW).

I think the .220 Swift is regarded as the fastest bullet on the market, and is typically around 4,000 fps (a 23% increase compared to the XM193, 33% compared to the SIG Fury), while there are apparently 4,250 fps (31% / 42%) versions available, and apparently handloaders can get it up to 4,500 fps (38% / 50%).

Barrel wear is ferocious, you need a long barrel (26" is standard, as I recall), and the Swift is simply not as accurate as the .22-250 (though the latter's more modern case design doubtless helps with that), a comparable though slightly less powerful cartridge.

[Rupert]

Originally Posted by David L Pulver

Yeah. In my design rules, pistol ammo is generally low-powered, meaning it's loaded at somewhat under half the maximum volume capacity for a given size of case, so uprated ammo can be quite significant change. In rifle ammo (or autocannon, tank gun, etc.) ammo the casing is already very nearly full, so the performance gain of stuffing the casing even more full tends to be minor at best. In GURPS terms, it's usually not worth worrying about.

One thing you have to watch when handloading is over-filling a case - you can generally still seat the bullet, as it just compacts the powder down. The fun comes when you fire it, as compressed loads tend to burn somewhat faster than normal, so you have an excess of powder burning faster than intended, which a resulting much higher pressure than expected...

[Rupert]

Originally Posted by David L Pulver

Again, this partly due to seeing how conservative regular firearm changes were at TL6-8 in terms of raw damage and range (unless the bullet is changed), at least in GURPS terms. But it's mainly due to being sufficiently lazy that I don't want to deal with creating whole new firearm stat blocks f or TL10, TL11, and TL12 versions of TL9 guns....

Blocks of guns, all alike aside from TL, and some minor stat changes with each TL are also unlikely to excite players and potential purchasers of a product including such lists either. Most players want their upgrades to have meat, or at least cool fluff. Going from a laser pistol to a blaster feels more of an upgrade than a 'laser with +1/die damage', even if that's essentially what the blaster is.