I'm wondering what types of firearms would be impacted if explosives and combustion in general were to have a random chance of being more potent or less potent. Could new firearms and/or ammunition be feasibly designed to adjust for this random variability?

More specifically, the setting/world I'm working on has electricity and the associated tech disrupted instantly, while the combustion effect discribed slowly builds over about 10years time. At first the combustion effect has a low intensity and a low chance of occurring distributed in a bell curve favoring normalcy, but over time the chance and intensity of the effect increase with up to 90% burn variability evenly distributed. Assuming that technology level at the start of the 10 years is identical or higher than our own world, which types of firearms,explosives and other combustion dependent weapons would break down first?

The effect impacts everything and anything that is capable of burning or exploding, not just things that were made after the effect started, although slower burning combustibles (Wood for example) are impacted to a lesser degree. The effect is global, and stays the same for a few seconds at a time before randomizing again.

The effect impacts living entities considerably less than inanimate objects(to the point that life is not directly disrupted by the effects in any noticeable way). It is also localized as much as possible to just explosion pressure and electricity.

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    $\begingroup$ You should go into more detail about exactly how combustion just magically becomes more or less potent. Is it a production change (in which case people would notice it happening) or is it a sudden "this round that has been in my closet is suddenly 10% more powerful than it was yesterday" type of thing? $\endgroup$
    – iAdjunct
    Jan 25, 2015 at 16:04
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    $\begingroup$ How is this science-based? Perhaps switch to using just a less restrictive tag like reality-check? $\endgroup$ Jan 25, 2015 at 16:56
  • $\begingroup$ iAdjunct, Good point, I'll see to it that I clarify a bit. $\endgroup$
    – Jonathan
    Jan 25, 2015 at 17:32
  • $\begingroup$ Serban Tanasa, I'm thinking that the post is still science based in that the question is how things change when a scientific law works differently. I'm asking how, assuming all other laws of science are still constant, things work differently. That said, I see your point, and I'll change the order of the tags to reflect your input. $\endgroup$
    – Jonathan
    Jan 25, 2015 at 17:37
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    $\begingroup$ How much does the explosive force vary? Does it double at the max? 10x as much? Some firearms will withstand/are designed to handle being overloaded/overpowered ammo (and might go up to double) - however, almost all of them will break at 10x the force. Having a gun blow up in your face, well, that'll take off your face. New guns can be designed, much heavier barrels, etc. To handle this problem... but it might be hard producing them if there isn't electricity (to do refining of some metals - and to run machines). You can hand-forge stuff, but that's a rare skill. $\endgroup$
    – user3082
    Jan 27, 2015 at 18:30

4 Answers 4


A firearm is - at it's core - a very simple device. In the most simple form it is just a cylinder closed at the bottom. You fill it with explosive, put a projectile on top, ignite the explosive and the expanding gas pushes the projectile forward. This basic principle hasn't changed much in the past 1000 years.

When you don't know how powerful the explosive is, you won't know how fast the projectile will be when it exits the barrel, so shooting at a target far away will be quite a game of chance as you don't know if your bullet will fly far enough. You also need to make sure that the barrel is stable enough to withstand the explosion even in the worst case that the explosive is as strong as it could be.

When muskets and cannons started to appear on the battlefields of the late middle ages, this problem was a very real one. Gunpowder could be weaker or stronger depending on how dry it was stored, the quality of the ingredients which were available to make it and how accurately they were mixed. Also, the operators weren't accurately measuring the amount of gunpowder to pour into their guns. So guns had to be designed to deal with this.

With the invention of half- and full-automatic firearms, the exact explosive power matters more, since they also use its power to drive the mechanics which load the next cartridge into the chamber. Not enough power, and it might not work and the gun jams. Too much power, and the mechanic might be damaged. The comfort zone between these two limits varies from model to model. Modern production methods for gunpowder made the quality of ammunition much more consistent, which is a prerequisite for making such weapons work reliably.

When you want your modern firearm to be really reliable even when your ammunition isn't, you better get a lever-operated or pump-action gun. They are usually designed in a way that even in case that the cartridge is a dud, the normal repetition procedure will eject it and replace it with the next one.

When you still want full-auto fire, you could drive the reloading mechanics with another power source. There are larger automatic weapons which use a motor to drive the cycling mechanic, but without electric motors or combustion motors, the only remaining option would be a hand crank, like the original gatling gun.

Another option would be to refrain from the explosive and pick another acceleration method. There are several options available which already exist:

  • Electromagnetism, giving you a railgun or coilgun. Prototypes exist, but they currently lack a use-case. Their main disadvantage is that they require huge amounts of electricity, so when you want them to be strong enough to be lethal, they will likely not be man-portable anymore. You said that electricity works even worse in your world than combustion, so this is likely not an option for you.

  • You can use compressed gas to accelerate your projectile, giving you an air gun. There are many of these commercially available today, but most of them are designed as non-lethal toys or sports equipment, which means they are usually designed for minimum lethality. However, with higher gas pressure and more lethally designed projectiles, the technology could easily be adapted for creating lethal weapons.

  • Mechanical energy stored by deforming elastic materials, giving you a bow, crossbow or slingshot - a family of weapons which has proven to be deadly and reliable for thousands of years. After the collapse of an advanced civilization these might again become popular, because these weapons and their ammunition can be made from readily available materials with no tools more sophisticated than a knife.

  • $\begingroup$ en.wikipedia.org/wiki/Chain_gun for automatics and semi-automatics. Not that you'd really bother with the chain part, but electric action would be quite practical and reliable. $\endgroup$ Jan 25, 2015 at 15:32
  • $\begingroup$ @VilleNiemi But how will you operate it without an electrical or combustion engine? You could use a hand crank like with the original gatling gun. Added this option to the answer. $\endgroup$
    – Philipp
    Jan 25, 2015 at 15:38
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    $\begingroup$ Right, the railgun confused me into forgetting that detail. Still, your edit is a good one, so no damage done. // There actually was (briefly) an air rifle (en.wikipedia.org/wiki/Girandoni_Air_Rifle) in military use, so it could be used there. And presumably to power the action? Don't think anyone actually did it, but pneumatic automation was common before electronics and with electricity falling off the grid, it would have experienced a renaissance. So a pneumatic machine gun? $\endgroup$ Jan 25, 2015 at 15:51
  • $\begingroup$ @VilleNiemi -- There are pneumatic M61 variants in full service, so yes, a pneumatically driven Gatling gun is quite feasible. $\endgroup$
    – Shalvenay
    Jan 25, 2015 at 16:51
  • $\begingroup$ Thanks everyone! this is exactly the information I was looking for. This makes a huge difference, You guys are awesome! $\endgroup$
    – Jonathan
    Jan 25, 2015 at 17:30

Sounds like you are building on Stirling's Change/Emberverse series and Boyett's Ariel. Great reads if you haven't already encountered them.

The challenge with such anti-combustion ideas however is that they change the observable symptoms (fire and explosions) rather than the underlying causes of that combustion (oxidation).

I'm not very current on the chemistry involved, but three decades ago when chemistry textbooks littered my dorm room floor, fire was taught to be an chain of exothermic reactions in which oxygen was added to an existing molecule's structure, yeilding enough energy to more than fuel the start of that same reaction in adjacent molecues.

Things burn slowly when the yeilded energy is just enough to set off a few chain reactions. Things explode when the earliest reactions yeilds enough energy to simultaneously set off chain reactions in all surrounding molecules.

Unfortunatley the oxidation reaction is common outside of open combustion including many biological processes which are needed to keep us alive.

So if some foreign entity somehow changed the physical laws of the universe to globally change how oxidation functions, none of us would be here to see if the guns still work. It cannot therefore be a change to the burning process, it has to be a change in the fuel.

So some entity selectively changes the strength of specific atomic bonds, making them stonger so that in molecules containing these bonds, the oxidation reaction chaining barely functions or doesn't function at all. That seems reasonable until you realize that the strength of those atomic bonds is important to other processes besides oxidation. Again the fragile structures of life fall apart and there is no one left to check if the guns work.

Sadly, it doesn't look like we would survive any physical law modifications which might result in a change in the combustability of gun powder.

From a world building point of view, changing the way combustion works is a tool for pushing your modern-day born characters into an age before Samuel Colt made all men equal. If you really want to stay reality based, you might be better served by an oil eating virus to destroy the economy and the ammunition assembly lines, followed by a global civil war to use up all the existing ammo.

The removal of firearms from a modern day apocolyptic has been used as the premise for some really great science-fantasy adventure stories. The fact that none of them could pass a reality check didn't make them any less fun to read.

So I say ignore the science and write it anyway.

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    $\begingroup$ As I recall it, Stirling's "Emberverse" doesn't change the combustion itself (thus bonfires &c work just as always). Rather, it's a change in the pressure law: the energy that would go into compressing gasses mostly goes somewhere else. So gunpowder burns, but doesn't produce enough pressure to propel a bullet, and you don't get steam engines and the like. $\endgroup$
    – jamesqf
    Jan 26, 2015 at 3:48
  • $\begingroup$ Good catch! I never made that connection, having quit after the first few books. $\endgroup$ Jan 26, 2015 at 4:13
  • $\begingroup$ You bring up some really good points, and although I hadn't realized at first, my idea was heavily inspired by Dies the Fire (The only Emberverse book I've read). While the end result is similar, there are differences. The two main ones are that the effect happens more gradually than it did in Emberverse. The next one is that the effect can amplify or nullify explosive/combustion properties, as well as function normally, it's a random chance between the available variables. Rather than having weapons stop working altogether, my setting has them stop working over time in order of complexity. $\endgroup$
    – Jonathan
    Jan 27, 2015 at 17:50
  • $\begingroup$ Best of luck with your creation! $\endgroup$ Jan 27, 2015 at 18:56

The whole idea of affecting combustion intensity and electricity to reduce us to the middle ages has serious drawbacks. Our bodies are essentially electrochemical thermodynamic engines. Tweak the laws of physics too far and we die. Or our biology is so impacted that:

  1. we become idiots or vegetables
  2. we become crippled
  3. we can't reproduce

The same quantum physical qualities of metal that give it good electrical conductivity also give it good thermal conductivity, ductility, toughness, and reflectivity. With electrical conductivity eliminated the other qualities will also go. No shiny armor and swords, no frying pans, mirrors, pretty silver chalices, or gold jewelry. Instead of a romantic Tolkienesque world you will have cavemen with sticks and stones.

The whole issue of combustion reduction revolves around one issue: catalysts! The right catalyst can accelerate chemical reactions. Also the types of chemicals used and the fineness of the particles will define the reaction rate. Also there are two types of explosion. Gunpowder just burns fast. Nitroglycerin actually decomposes at a rate faster than the speed of sound releasing chemical energy. Big difference. Look it up. Compressibility gas laws and thermodynamics don't just affect machines. They affect our planet's thermal balance and our climate. Reduce heat transmission through the crust and we could see a supervolcano start up. Change the compressibility of air and sea life could die, forests could become deserts, and supertornados could sweep across the planet.

  • $\begingroup$ You bring up a few good points, Mainly that anything that would disrupt electricity and firearms would also disrupt most biological organisms and large scale geological patterns as well. My counter to this issue, is that the effect does not impact events beyond a certain scale, and applies to a significantly lesser degree when applied to living organisms. With that said, I'll edit the question to include that point now that you've brought it up. $\endgroup$
    – Jonathan
    Jun 3, 2015 at 22:30

To add to the other answers, a major problem I didn't see mentioned anywhere is if the pressure produced by burning gunpowder drops too low, the bullet won't even exit the barrel of the gun. That's what happens when you under-charge a cartridge, or forget to add powder entirely so the primer alone propels the bullet a short way into the barrel.

If you don't notice the squib round and fire the gun with a firmly plugged barrel, the result can be anything from just a slightly bulged barrel to a catastrophic failure that completely destroys the gun and injures or even kills the shooter. That's the way things work in the world as we know it.

Add the possibility that the internal pressure could go from way too low to way too high in a short time--if I understand your scenario correctly--and I would not want to use guns at all anymore. It would be like using grenades where the fuse could vary from 0.1 to 10 seconds and you'd never know which it was going to be until you'd already released the spoon.

Edit: I should add that in the event of a squib, a semiautomatic or automatic weapon is not likely to chamber another round (or recock the bolt in the case of open bolt weapons). They can, but squibs are more likely to go unnoticed in relatively low recoil, manually operated firearms, or externally powered automatic weapons like chain guns and Gatling gun descendants.

  • $\begingroup$ For that very reason, firearms become more and more dangerous as the effect increases in intensity. Guns could be made that would take into consideration lower or higher pressure rounds, but these too would become unstable as the effect nears it's maximum potency and levels off. Automatic firearms would probably be a thing of the past rather quickly, and even semi auto and single shot guns would be too dangerous to provide any real combat advantage. $\endgroup$
    – Jonathan
    Jun 3, 2015 at 22:39

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