Logical in-universe reason for humans to continue using conventional firearms while other species use exotic weaponry?

Question

In my world, I planned for humanity’s soldiers and civilians to use conventional, chemical-propelled firearms. There are changes of course (ETC ignition became common, more lightweight materials, telescoped ammo, and high-tech sights) but other than that, they still rely on the same old principle of “propellant lit, bullet go forward”.

Here’s the thing: since humans use more traditional weaponry, I wanted my aliens to use more ‘alien’ weaponry. Exotic stuff such as lasers, plasma, proton beams, so on. But here’s the thing: each species would logically want to use the most efficient weapon.

I wanted to have it so that the human weapons were almost as effective as the alien ones, while costing less energy. But that brings up the question of why the aliens would be using the energy weapons in the first place.

Is there a way I could create an in-universe reason for the aliens to use energy weapons (ie they have specific advantages over firearms while not being completely superior)?

Answer 1

Divergent Resources = Divergent Technology

We humans evolved on a planet where celulose evolved millions of years before the enzymes required to digest them came into being. For this reason, or other various factors, we have TONS of fossil fuels which might be exceptionally rare on other worlds. We also have a lot of the elements you would get from, sources like exploding white dwarves and supernova, but an alien world that formed in the wake of an exploding neutron star or low mass star might have a lot more of certain elements that are pretty rare on Earth like xenon, tungsten, lithium, and gold to work with which would make high energy electrical components much more accessible.

Basically, when Humans entered our industrial revolution, we switched from a cottage industry reliant on wood and charcoal to one based on petro-chemicals which incidentally made our crappy musket type weaponry cheap and easy to develop into the assault weapons, missiles, and long range cannons we have today.

Most alien worlds however may not have had a Carboniferous Age; so, when they entered their industrial revolution, there was no coal or petroleum to work with. Basically, a lack of fossil fuels meant that their scientists would have very few petrochemicals to experiment with like humans did. So, where we went for things like internal combustion engines, and coke stack smelted steel, they went instead for things like solar powered electric engines, and electrolysis smelted aluminum.

Because of this disparity of resources, you don't just get different costs, but you also get a disparity in how much effort has gone into studying these resources for practical applications. So while human history is full of petrochemists and a relative handful of electrical scientists, your alien history would have a lot of electrical scientists, and very few petrochemists.

So, when the aliens see a human assault rifle, they don't see a primitive back-water weapon, but rather a highly advanced piece of technology made out of exotic materials. On this level, their perception of a gun is exactly the same as our perception of a laser. These weapons are comparable because both races have invested the same amount of time and effort over hundreds of years to get really good at making weapons this way or that, and once you find something that works well, it's hard to introduce a more experimental alternative that costs more and lacks the maturity to be as good. So, both races continue to make THEIR weapons, even as space travel makes both sets of resources more attainable.

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Matthew's answer also brought up one of my favorite sci-fi quotes ever, but missed one of the most significant details of this quote that makes it so good:

"The Asgard would never invent a weapon that propels small weights of iron and carbon alloys by igniting a powder of potassium nitrate, charcoal and sulfur."

~ Thor (Stargate SG-1)

Not only did the Asgard not think to make kinetic weapons, but they showed a sheer lack of understanding in regards to ballistic technology by thinking we would use steel bullets. They also seem to have missed the fact that we stopped making weapons grade gunpowder from potassium nitrate, charcoal and sulfur over 150 years ago. In this quote, it seems that the Asgard tried to assume they knew how to make a human gun based on what they knew about our technology in general and maybe some historical records, but if they tried to make a gun that worked in this way, it would be an utter piece of garbage... and that is assuming they could get all the other stuff right like riffling, gas repeaters, percussion caps, etc.

Likewise, if your aliens think as the Asgard do, then if they try to make their own knock off versions of ballistic weapons, they will remain sub-par compared to their human counterparts barring a lengthy period of R&D.

Answer 2

Both kinds of weapon are dangerous for the soldiers of the other side

Bullet based weapons have a strong recoil*. Humans have a skeleton and a structure that allows to withstand the recoil without damage.
If the aliens are a kind of octopus or mollusk, they would find it difficult to shot a rifle without being injured by the recoil (and developing a recoil-less technology would seem to them a waste of time and resources).

At the same time, plasma weapons use a technology that is inherently unreliable: there is a small chance that the weapon explodes, killing the soldier. Aliens have a hive mentality, so the small chance to die killed by own weapon is an acceptable risk, while humans would never bear it

Answer 3

"The Asgard would never invent a weapon that propels small weights of iron and carbon alloys by igniting a powder of potassium nitrate, charcoal and sulfur."

A long time ago, your aliens perfected kinetic defense to the point that "traditional firearms" were all but useless. Generations passed, and the aliens, who haven't used such weapons in a very long time, stopped defending against them and forgot about them. Everyone uses and defends against energy weapons. Meanwhile, those plucky humans came along and... their kinetic weapons are quite effective.

This is a standard trope in science fiction.

Okay, so that covers why the humans don't just get their sorry backsides handed to them. Why, then, do the aliens use energy weapons? Well... https://scifi.stackexchange.com/questions/59995/ has quite a few suggestions, though the above also gives another; because at one point, kinetic weapons became useless. Since energy weapons still work, why change what isn't broken? (But also, all the other reasons in other answers here and in the question earlier in this paragraph.)

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Since some comments are complaining that the aliens will just start defending against kinetic weapons again, let me explain in more detail why they might not.

• First off, note again the suggestion that they forgot how. It's been a long time since they had any need to do so, and the technology that gave them near-perfect defense may be lost.
• Even if they didn't forget, if they don't just conveniently have the defense systems lying around in their forward depots, it's going to take time to get them distributed to the front line. That assumes that they have them mothballed somewhere. More likely it will take them years, even decades just to spin up the necessary manufacturing capability again.
• Alternatively, defensive systems usually come with drawbacks; mass and/or energy penalties, if nothing else. Maybe they have to choose between a defensive systems that makes them invincible against puny humans, but leaves them completely vulnerable to some other opponent or potential opponent, versus having good protection against energy weapons and so-so protection against kinetic weapons. (Maybe the reason they stopped using kinetic defenses in the first place is because their system likes to blow up if you merely wave an energy weapon in its general direction.)

Answer 4

Supply chains
Humans have been using projectiles weapons and have manufacturing processes for them. We dabbled in portable energy weapons but never could perfect them enough to overcome their drawbacks, so it was more practical to continue using what we knew.

The Aliens must have figured out some exotic energy source that is stable enough to power Portable Directed Energy Weapons (and not explode like a super-grenade).

Humans can't recreate their tech yet, or don't have the unobtainium required. Maybe the Alien weapons have fail-safes so they DO detonate when they fall into the enemy's hands.

Answer 5

Efficiency in different ways

Now lots of people will probably give answers that firing plasma and other energy weapons aren't effective or incredibly difficult to implement. For your story I'll assume they do work.

Efficiency can be thought of in many different ways. Making of the ammunition, shipping and effectiveness against different targets.

Imagine both sides have the technology for energy and conventional weapons, which are equally effective. They will use what they have infrastructure for. If you already have large amounts of factories and knowledge in your armies on how to use them, you would not go for the other weapons suddenly.

But building it can have their own problems. Possibly the resources to build conventional weapons is much more prevalent for humans, while the resources to make abundant batteries or other energy holding/discharging resources are easy to come by.

In relation to that they might focus on less weapons and military, but with higher effectiveness. That means higher resource cost and time investment for effective troops. Humans might just build a ton of weapons. Much like Germany vs Russia in WWII. Russia had much less modern and effective tanks than the Germans. They did have good front armour at an oblique angle and ok guns on their tanks so they could damage the German tanks. They had parts found in tractors and the like, making them easy to repair and build in their massive factories. And they fielded so insanely many tanks that the German tanks were simply overwhelmed. This made them exceedingly effective for multiple engagements, while individually they are very much lacking.

There might also be a certain doctrine against a certain enemy. We can see in the HALO series that humans have conventional weapons, while aliens have energy weapons. This is correct for them, as humans only had unshielded humans to fight against. The bullets are great at penetrating flesh, but not shields and does little against electronics. The aliens however often have shields on their individuals and vehicles. Energy weapons are great to take out shields and electronics, while being slower to damage flesh. They still have some aliens that don't use shields and you see they often have some flesh penetrating weapons added. They didn't know each other before, so the effectiveness of their weapons is based on what they encountered. Themselves.

Even if conventional weapons would be less effective you might continue to use them. Difference in tactics can determine a great deal. See the Vietnam war. High tech and overwhelming forces lost to an enemy who knew the land and had older weaponry, with a few exceptions like the AK47, which was everywhere at the end of the war. Even if they could've used modern tanks and artillery, it might've lost them the war. Their strength was invisibility, guerrilla tactics and psychological warfare. Your human tactics might be with conventional weapons also because of tactical reasons. Maybe the loud noises, flashes and explosions more than make up for the lack of effectiveness. Humans are trained to be used to it, while the possibly more effective, more quiet and less flashy energy wielding aliens might go straight to panic when a pistol goes off.

Answer 6

Simple solution: the exotic weapons aren't any more effective than the projectile weapons overall, when you take into account things like logistics, durability, field operations, and weapon characteristics. There's a rock/paper/scissors relationship, and as a result there's no real benefit to either side switching to what the other side uses when their own logistics and training is set up for their own weapons.

Hypothetical example: say one side uses portable energy weapons, powered by a non-removable battery pack and firing an energy blast with similar characteristics to a laser in terms of speed and particle mass vs humans with combat rifles. Because of the technobabble technology used, field-replaceable battery packs aren't optional.

In damage, not much difference. Getting hit by the energy blast and hit by the bullet will both ruin your day. In terms of penetration, a wash as well. They both have similar characteristics, so you're not blasting a hole through a half-meter of concrete to get the enemy on the other side.

Advantages the energy weapon has over the rifle: the battery last a hell of a lot longer than the number of magazines the soldier can carry on them, so for a given mass, the alien will be able to shoot a lot more. Also, because it shoots some kind of energy, it isn't going to be effected by bullet drop, time to impact, wind, or many other environmental considerations. Essentially, if you can see it, you can hit it.

Advantages the rifle has: it doesn't have to be recharged. As some point the alien weapon has to be connected to an power source, and power sources make targets. A pile of magazines or cases of bullets are inert and thus can be stockpiled and not attract any attention, and in combat can be brought forward to the soldier on the front line so they don't have to move to continue fighting. The alien has to be pulled back for the weapon to be recharged, or else a new weapon brought up to him. This makes logistics more complicated because you need a greater number of weapons per soldier, or tie them down to some kind of infrastructure. And it might be able to have a faster rate of fire because the energy weapon has to cool down between shots or the heat builds up too rapidly, preventing it from doing something like firing the equivalent of full-auto, meaning that while a combat rifle can fire single precision shots and can also lay down heavy suppressive fire, the alien weapon cannot.

So you've got a situation where each weapon system has advantages in specific situations, but overall the whole things balances out so there's really no net benefit to switching over to use the same weapons the other side does.

Answer 7

Ethics

The aliens have their own notions of ethics, which regrettably do not exclude killing humans, but do exclude risking the lives of one another. They cannot countenance firing a bullet and leaving it to make its own way in the world. They need beam-based weapons that lock onto a target with particles travelling nearly at the speed of light, and continually verify they are damaging only that target. The technology uses a lot of power, but it is still cheaper than trying to deal with the bad press that follows a friendly fire incident.

Answer 8

The simplest answer may be available energy density.

Humans have been using chemical energy storage for a very long time now. From the first piece of firewood to the latest chemical explosives, we've been gradually increasing the energy density of our fuels and propellants. More recently we've been trying to find other ways of generating and storing energy that are not reliant on nasty chemicals, but our best solutions to storing energy are still chemical. Electric cars store energy in batteries as chemical energy, because it's by far the best option we have available to us at the moment. Even then it's far more effective - if more polluting - to run a car directly on chemical reactions than to use batteries to drive electric motors.

The same is true for weapons. Yes, we can theoretically create a capacitor-powered man-portable coilgun (or railgun), but the energy demands are so high and the storage density of capacitors so low that a power pack capable of a single shot would outweigh the rest of the weapon... and probably the person wielding it. Meanwhile a 7.62x51mm NATO cartridge carries a chemical charge of about 3.5 grams, capable of sending a 10 gram round down-range at about 850 m/s, purely by hitting a primer cap with a tiny metal hammer.

The aliens on the other hand have long out-grown the need to store their energy in crude chemical propellants. They have direct energy storage capable of much higher energy densities than we poor humans can even comprehend, allowing them to store a few mega-joules worth of energy in a device about the size of a standard 30-round M4 magazine. Or perhaps they have discovered (or created) a material that can be readily converted to pure energy, or a way to tap into zero-point energy, or a clean and efficient method for creating and storing antimatter that can then be used to produce energy through annihilation with normal matter. Whatever the actual method, the aliens have a way to carry around power for their weapons that has an energy density on par with - or better than - the best chemical propellants known to man.

Not only that but they have perfected the necessary superconductors and insulators to allow them to use that energy efficiently. All of this is based on technologies that the humans don't have access to, and materials that humans don't even know exists.

In order to switch to energy weapons, humans would need to learn a lot of material technologies that are old hat to the aliens. Power generation, transport and storage would all need to be greatly improved. Then we'd need a way to actually use that power in big bursts without melting the equipment or letting any of it go where it isn't wanted: superconductors and (near-)perfect insulators.

In the meantime, we still have all those factories churning out the weapons and ammo we already know how to use. We have a lot of slightly crazy people figuring out new and interesting ways of constructing bullets to screw with the aliens too. Alien force fields messing with your day? Turns out when you hit them with buckshot the sheer number of tiny bits of metal makes the shield controller circuits freak out and they have to reboot, giving you a quarter of a second to hit the armor underneath. Oh, the armor is too strong for buckshot to penetrate? Not to worry, we put a depleted uranium penetrator in back of that buckshot with a handy proximity fuse to make sure you get the perfect 1:2 shot every time, or your money back. And if you buy now we'll throw in a camo tarp guaranteed to fool alien sensors with every case, free of charge. How many can I sign you up for sir or madam?

Uhhh... sorry, my inner sales-bot got out for a moment there.

In the end we'll stick with guns and bullets until we find something better, we run out of people who can make and use them, or until we find a target that they just can't affect. If your aliens have overpowered defences that can shrug off the best bullets we can make... then we might as well just throw a big party to welcome our new Alien Overlords.

Answer 9

Vulnerability

Aliens are a way more prone to get damage from energy weapons, so in the moment they discovered first energy weapons (say electro-shock - stun baton - taser) they had "ultimate weapon" in hands and then they invested to make it better on one side, make shields against it on other side and soon they come to all the lasers, phasers, aliensers with long range attacks and also to energy shields to protect agains ranged attacks, maybe with basic latex armor under to prevent contact energy weapons.

With so powerfull weapons at hands, knifes, swords etc. was just primitive technology, mainly dead weight if you can imagine, what could do batery driven taser of the same weight.

Now aliens are nearly immune agains simple energy weapons, as their shields are able to synchronise really fast, so the arm race is about variable frequencies, polarised lights and more complicated ways to overcome those shields. This leads to all those strange emitors, subemitors, concenrating rings and energy modificators on their weapons.

Humans are prone to energy weapons too, but not nearly as much as aliens are. So AAA batery powered taser is not deadly threat, but just childern toy. Knive on the other hand ... and gun and canon ... and big steel shield as counterpart (well it could be melt by energy weapons, regardless frequency hoping, just by pure energy - but it still takes a lot of energy to melt a civilian car)

And while aliens are little more resistent to simple knifes (as their bodies have totally different construction and multiple organs), swords are problem, as well as chainsaws. Long burst from assault rifle is totally deadly and lead ignore all energy shields and latex.

And mass production of rifles and swords is a way easier, then massproduction of super pasers with frequency hopping and polarisation effects and stroboscopic.

So it is on you, how to balance this two approaches, hight tech low-but-sofisticated energy and brute force hard alloys - maybe we are totally superior (after rediscovering flags instead of walkie-talkies), and they have to build all the industry to get bullet lead from escavated prehistoric inefficient accumulators and steel, which have use just similar to our use of silver for jewelry ...

Answer 10

You don't bring a lead-slinger on a spaceship.

The aliens arrived in spaceships, so they wouldn't have brought conventional projectile weapons with them on the journey. A stray bullet could puncture the hull and depressurize the ship, killing everyone. They'd have energy weapons that can easily do lethal damage to organic matter without posing a risk to the ship. You might also have an enriched oxygen environment on the ship, and using a firearm might actually result in a fire, one of the worst things possible in space.

Even if you don't plan to get into a firefight onboard your ships, there's always the risk of a poorly-maintained firearm going off unexpectedly from heat or jostling - too much of a risk to even store those on a spaceship, let alone allow everyone on board to be armed with them.

Now maybe they have firearms similar to ours on their home world, and of course nothing stops them from acquiring and using Earth-made guns once they get here, though if they're the type of aliens that look alien enough that they can't easily blend into human society, it's possible they'll have a harder time getting Earth weapons, or maybe their hands or whatever appendages they possess just aren't compatible with Earth guns for whatever reason (fat fingers? tentacles? lack of opposable thumbs?), so they'll just stick with what they brought with them.

Answer 11

Alien weapons are extensions of alien bodies.

The energy weapons can be powered by the aliens themselves, and are similar in many respects to the inborn biological weaponry of the aliens. These weapons make sense to the aliens because they are really augmentations of the aliens themselves. The aliens do not need to carry ammo or batteries to use them. For the aliens, attacking with their energy weapons feels as natural as hitting something with a stick is to a human.

For an alien there might actually be more to using an energy weapon than just zapping something. Their electromagnetic senses extend through the output of the weapon. A hit on a target (or near a target) also provides information to the alien about the target or energized region. Aliens also use their "weapons" as sensors.

Answer 12

Reliability vs Repairability, and/or Tactical Differences

Plasma weapons/proton beams/lasers are hugely reliable compared to human "slug throwers". The mechanisms are solid-state, and the only moving part is the trigger and the latch that keeps the fuel cell/magazine in place. No bolt, no residue, no problem. It works underwater, on land, in space, you name it. But that doesn't mean the things are indestructible, just that they're low-maintenance compared to a human gun. The downside is, when they DO develop a fault (because that much power/plasma/whatever will eventually wear out the components) it's DEAD. Throw it away, get a new gun.

Meanwhile the human rifle isn't quite so rugged. You have to clean it fairly regularly, it can fire underwater/covered in mud but is more prone to jamming in those conditions and so on. The upside is, you can FIX IT. Soldier can disassemble it and clean the insides, and because there's no electronics at all it's less susceptible to certain types of extreme environment problems. And if a piece wears out you can replace that single part rather than the entire weapon, which has strategic implications. (Humans can fix 300 rifles with 100 spare rifles, but aliens would need 300 spares, for an oversimplified "strategic implication.")

Or it could be a matter of ammunition. Perhaps a laser/plasma weapon can store fewer lethal shots in the same amount of mass. A 1kg pile of human ammo is 400 rounds, whereas it's only 100 shots of laser/plasma weaponry because batteries/plasma containment tubes are heavy. But the aliens are bigger/stronger and CAN carry 400 rounds of plasma ammo but the smaller humans (who also think 400 rounds is what an infantryman should carry) stick to lighter-ammo slug thorwers. After all, the killing power is almost the same, and it's better to have a weapon you need to clean occasionally than one you run out of ammo for!

Or maybe there could also be Tactical reasons behind a choice of weapons, and the aliens are happy to carry fewer rounds that pack more punch. As it stands, "Suppressing fire" is hugely important in warfare, and has been since forever. Humans duck and that means even if you don't hit one the simple act of shooting helps. Military tactics have evolved from that and most shots are sent "in the direction of" the enemy, rather than "aimed at" an enemy. That's why the M16 has a 200 rounds a minute max rate of fire and is only accurate to about 350 yards. But it wasn't always like that. WWI American doctrine believed americans were better shooters than their enemies, and therefor the US made infantry that could shoot 1000 yards accurately and were told only to fire when they saw a target. There was actually PUSHBACK against a semi-auto rifle because it would encourage soldiers not to aim. Turns out none of that was true, so they started making faster-shooting but less accurate weapons. But maybe it IS true of your aliens, so the slower-to-fire laser or plasma weapons pay off for them, where they wouldn't for human infantry. Your aliens can take those 60 aimed shots and make as many kills as a more jittery human soldier with 400 rounds.

I should point out these ideas aren't mutually exclusive. Once a war gets going with whatever weapons they have it's also HARD to change over mid-war. Doubly so if the weapons are so different in design and manufacture and supply. So if any of the above is true in human v human or alien v alien fights, once they meet each other they'll keep using what they've got because the inertia of tradition/logistics may very well outweigh the benefits of a changeover. Like the Japanese with their terrible bolt-design of their WWI infantry rifle. They knew it was bad but had no time to change it. Or the US Army in the American Civil War, whou COULD have been equipped with breech-loaders in 1862/3, but didn't have the logistics or political will to make it happen.

Answer 13

COST.

Simple. Cost. It still costs too much to create and mass produce weapons with exotic power sources and discharges. Maybe humans have a few, like cannons mounted on space ships, but for the most part its just too darned expensive.

Not to mention the fact that they still haven't cracked how to do it on such a small scale for guns and rifles. Maybe they'll get to it one day, but as of right now, too expensive and too much trouble.

Also, bullets still work just fine. They still do the trick. A single bullet may not break through an alien's force field, but several bullets break the force field down enough that finally a bullet gets through and bingo "that's a kill!" Fortunately, "them bullets is easy to mass produce, so we's gots lots of 'em!"

Answer 14

Equipped for Different Operating Environments

Energy weapons will perform more poorly in many environments than projectile weapons, and vice versa. Atmospheres, especially thick and humid ones, will interfere with beam propagation much more than they will affect a bullet's trajectory. Smoke, fog, heavy snow, or high humidity may significantly reduce a laser's effective range and firepower.

In space, beam weapons do not have these problems, and they have other advantages such as a lack of recoil that must otherwise be compensated for. Meanwhile, projectile weapons require ships to carry the extra weight of ammunition, and extra weight is expensive. Projectiles also have disadvantages after the battle is over: lots of spent projectiles in orbit leads to collision hazards for years, if not centuries.

Thus, aliens who come from lower gravity worlds with lower density atmospheres or worlds with more predictable and less extreme weather might see much fewer drawbacks with energy weapons than humans, living on earth, did. If they do more space travel than humans, or have been at it longer, they may have adapted to energy weapons because of their particular advantages in that environment. Humans, meanwhile, have learned different lessons in weapon's development.

Thus, each race has built it's military and logistical chain to support the weapons it favors, and this is not something easily changed in the course of a war. The logistical situation may be such that, even if a beam weapon or a projectile weapon is more suitable for a particular environment, the advantage may not be great enough to warrant the supply disruption, or stockpiles may simply be unavailable.

Answer 15

The alien energy weapons require Helium, and we're all out of Helium.

With current usage we're likely to run out of helium in 25-30 years. Aliens will of course have their own sources. It's not far fetched at all that the energy weapons require helium in their manufacture, or even usage. Humanity could have access to the tech, and even have a few energy weapons, but while Helium is possible to artificially manufacture it's extremely expensive to do so. And it's needed in medical devices, as well as chip manufacturing and more. Diverting the small created supply to military use would be unlikely to happen just because the supply would be mostly insufficient compared to the need and further already needed elsewhere.

This would result in the military having maybe a few (especially vehicle mounted) energy weapons, but mostly relying on traditional arms.

Answer 16

You can't make the weapons incomparable or you defeat the purpose. Someone suggested the aliens have defeated bullet-technology. Well then humans would be non-competitive.

Shields protect against high energy weapons, so a kinetic weapon has an advantage there, the mass is much higher than the energy involved. If anything the shield just turns the mass into a molten mass like sabot round.

Aliens still use shields even though tactically they shouldn't.

As for beam-weapons versus kinetic weapons.

Humans don't have a lot of defense against the beam weapons so aliens have no reason to adopt them and already have the beam weapons-industry built so aren't going to retool everything to switch to kinetics.

Humans have the kinetics and against shielded opponents are not a disadvantage so the incentive to develop beam-weapons is much less.

Alien strategies and tactics developed millenia over vast deep space conflicts with little logistical capacity. The colonial wars in far flung worlds require minimal industrial effort or minimal supply lines so beam-weapons are favored.

Humans are on defense so they have access to all the resources and control the access, so they can mine the kinetic materials required.

Other things I saw as answers are also not really that good (not to poo-poo anyone).

Ammo vs. recharging? There's no difference. You can only carry so much ammo. It is MORE LIKELY that an alien can fire many more shots than a human can simply because power density is much greater than mass density.

Microwave power-beaming could remotely recharge your beam weapons in the field.

Tactically, humans could be forced to take out the "microwave battery tank" before really engaging an alien infantry force...so that their ammo can at least be limited.

A beam weapon would have a much higher rate of fire. Suppressive fire would be much more practical than a machine gun.

Machine guns are designed to pepper an area, a beam weapon can be designed to do the same only it'd do it more precisely with a computer generated algorithm that would ensure the most volume of area at a precise distance is filled by a pattern of beams flooding the area per second.

Ultimately, the only advantage a kinetic weapon has is it "does the job".

Because beam weapons take so much more to integrate, use, and maintain (such as the microwave battery tanks to recharge), a soldier might capture beam weapons but only be able to use them a limited time.

Developing beam weapon technology can be a priority of humans but its not useful now.

Keith Morrison mentions tanks, he's wrong about tanks.

German tanks were inferior to both Shermans and T-34s, the only thing that was good on them was the gun and ironically the German 88 flak gun out performed every German tank because it was also a superior gun.

German tanks were hand-built and hype. The hand-built custom build caused the tanks to be unserviceable. Their heavy armor meant they had a longer lifespan but that just meant they broke down in the field.

Russians knew their tanks wouldn't last more than 19 hours in combat so they didn't bother to build transmissions that would last longer than a minimum time, something like 20+ hours. So it's a misnomer that Russian tanks weren't well built. They had no reason to build certain parts better when battle attrition would make them explode.

Germans had great engineering, but their tanks died like all the rest.

Tigers never fought shermans on the western front, Fury is a myth.

Shermans were excellent tanks, well built, well machined, standardized parts so they could be repaired in field, and their armor was sufficient. The idea they were "death traps" has more to do with ALL tanks were death traps.

The attrition rates between Shermans and all German panzers was about 1:1 ratio.

Answer 17

Well for one thing even by today's standards modern weapons are primitive, consider the case of fingerprinting and serial numbers. This would also assume that some body would have to keep track of gun registries, I would imagine it would be easier to mass produce energy weapons because their less bulky. Easier to conceal thus require no traditional ammunition, you would also have the advantage of quicker response time. They might even be safer to store and handle if Star Trek has taught us anything. On a starship I would imagine a loaded gun to be both a fire hazard and a danger to crews living in space, imagine a bullet ricocheting off the bulkhead and causing a puncture in the hull. You would then have an even larger crisis, you would need to deal with heat and oxygen deprivation. Not to mention the spontaneous loss of atmosphere, thereby killing every living thing aboard the ship or space station.

Answer 18

I'm just adding a consideration to add to the existing answes.

Any sci-fi premise where the main combattants are sentients rather than computers and drones is already not based on potential future reality, so for starters if you say that t0he weapons are equal they simply are. Its no bigger leap than having evolved sentients fight each other with almost WW2 style weapons and combat.

That said, your aliens and humans have simply had a divergent weapons research with a similar eventual outcome. For example:

Lasers are nice because of their high muzzle velocity. They are held back by atmospheric disturbances and possibly tailor-made smoke grenades and the like, so for longer ranges plasma bolts were created. Plasma might not cut through an opponent but their effects can still go through armor, leaving charred craters rather than long cuts.

Humans in the meantime spend more time developing their bullets. Gyrojet bullets (rocket-propelled bullets) are now cheap and reliable, reducing recoil and allowing for high velocities (again, the gyrojets have been further developed than the low-velocity low reliability that current gyrojets represent). You could add layered mechanisms to fire the bullet, for example initially the bullet is fired by a normal charge before the gyrojet takes over or launched using railgun technology. The bullets could also be miniaturized bombs, such as mini shaped charges or using highly corrosive sub-coatings to cut through armor more easily.

The ability to cut through some armor or deal damage changes based on what weapon is used, but on average the weapons have similar utility in a fight. So both aliens and humans are content with the weapons they have and see no reason to go through the expensive and time-consuming process of getting their technology and industry on the level of their opponent just to field similar weapons.

Answer 19

This sounds like variation on "why bring a knife to a gun fight", to which possible answers include:

1. reusability and lack of re-supply issues;
2. surprise factor during combat;
3. the sheer joy of watching from up close as your enemy realizes (a) oww that hurts and (b) oh no, I'm dying.

(Ok, there's not much difference between a crossbow, a gun and a blaster on point 3.)

Firearms are a lot more practical when you have a planetary industry dedicated to producing standardized projectiles.

Otherwise if you have to use what you can collect as you go along: rocks are plentiful, knives and arrows are easy to extract from previous victims, and sunlight (or fusion power) is readily available even in space, and the equipment you need to carry along is a lot smaller than an ordinance factory.

Answer 20

Logically, since Earth-like weapons are effective against your aliens, then those aliens would research how to develop those weapons if they ever had to fight each other. And logically, aliens would research how to defend against Earth-like weapons if those weapons were (or had the potential to be) used against them. In both offense and defense, they would have a strong motivation to do such research - it would be a matter of life and death.

It's not plausible that a life-or-death motivation would have been ignored for your aliens' entire history, so we must presume that developing such weapons and armour has not been a matter of life or death for your aliens, at least until they started fighting humans (and now there's not enough time to start a research program from scratch, though they might be able to come up with some primitive defenses against bullets partway into your story).

We can conclude that:

1. Your aliens are peaceful at least amongst themselves, they do not fight each other so they have not had to develop Earth-like weapons for their own use. Their military exists only for fighting other alien species and defending themselves from external threats, and their enemies (until now) haven't been sufficiently vulnerable to Earth-like weapons for those to be worth developing and deploying.
2. Your aliens simply haven't been up against Earth-like weapons before. Your aliens' prior enemies aren't vulnerable to Earth-like weapons so those enemies haven't developed those weapons for intraspecies war (and hence didn't have those weapons readily available for interspecies war); and your aliens' prior enemies haven't figured out that your aliens are vulnerable to those weapons because, not being vulnerable themselves, they didn't think to try. It would help if your aliens haven't had much reason to do interspecies war before, so their prior enemies didn't need to research much about their vulnerabilities.

Alternatively we could conclude that your aliens did try to develop Earth-like weapons for fighting amongst themselves but weren't able to; that strains plausibility, since it's not that hard to fling something heavy or fast at something you don't like, but it's not logically ruled out.

Answer 21

Differences in tactical doctrine

There are a number of reasons why different armies would prioritize different aspects of weapons. Here are some examples:

• Weight. One form of ammo is heavier: bullets or batteries. How many shots can one soldier carry? Is one species stronger than the other? How long will a soldier on each side have to lug it around?

• Longevity. One army may run more long term field missions than the other. Which ammo can be more easily supplied to soldiers in the field? Which kind of weapon is more durable when you wade through a river with it? Can it be repaired easily? An army that uses guerilla tactics will be more concerned with this.

• Stealth. If one side is more prone to ambush tactics they may favour the quieter weapon.

• Cost. Which is better: A thousand super high-end weapons or ten thousand basic but effective ones? Every army strikes a balance based on the resources and materials available to them.

• Supply lines. Weapon 1 is the absolute best but can only be sourced from one place in your territory. Weapon 2 can be sourced from 10 places. If the source of weapon 1 is captured, your whole army must resupply and retrain with a new type of weapon in the middle of a war. The smart leader will choose weapon 2, to avoid this risk. Each side controls different resources that force them to choose different weapons.

Answer 22

The aliens did not invent their weapons, they stole/copied them.

You may be interested in the man kzin wars by Larry Niven. the Kzin did not invent their technology, they stole it from a species that tried to enslave them and found Kzin survived a lot better in their own environment than they did. Thus the Kzin have advanced technology but not all the precursor technologies that lead up to them. they can make gravity ships and lasers but don't know how to make missiles and effective slug throwers because the aliens the overthrew did not use them, and the Kzin are not big on research for just knowledges sake. The kzin did not even know reaction drives were a thing until they met humans.

Alternatively in the Uplift series by David Brin aliens inherited advanced technology from the species that uplifted them, and almost all species are uplifted from caveman technology. Very few species evolve and develop tech naturally. So most aliens lack low and middle technologies. they have spacecraft but not airplanes. plasma rifles but not shotguns. because most technology has been passed down by uplift, tech that is too primitive never gets passed on even if it is useful.

TVtropes has a whole page of similar examples. https://tvtropes.org/pmwiki/pmwiki.php/Main/AliensNeverInventedTheWheel

Answer 23

Form. The aliens are quadrupeds. Their exotic guns require a barrel length that's impractical for a human soldier to use, while they can carry it beside their body and aim with a periscope, rather than aiming directly along the barrel as a human would.

While such a weapon could be vehicle mounted by humans the combat normally doesn't involve them because they're too much of a target. A practical version for infantry combat would be a crew-served weapon and that's not worthwhile. Two humans with rifles are better than two humans with one exotic gun, but one alien with an exotic gun is better than one alien with a rifle. Thus neither side adapts the technology of the other.

Answer 24

The aliens have simply no idea how human weaponry works.

Oh, believe me, the aliens WANT to use the humans' weapons. They just have no idea how to make them. They've tried reverse-engineering them, they have strange components made of even stranger materials. They've tried stealing the weapons, they don't have the proper knowledge/body structure to use them. It's a simple answer, but an effective one.

Answer 25

An ammo round is very self contained. A gun is very simple.

Downsides:

• It takes time to traverse the distance between, so is less useful in long distance combat. Compare to a laser which is line of sight for miles. (Although one intense enough to do damage gets fuzzed out by air and dust.

• It has recoil. Using a rifle in zero G will be challenging.

Upsides:

• Chemical energy, at present, is our most economical dense way to store energy.
• Very long term energy storage is possible, meaning that you don't have to have energy generators on the front line.
• Training is quick. A few thousand rounds separates a novice from an effective soldier.
• Guns are not delicate (most of them). Present laser tech to deliver a combat rifle's rate of energy will NOT fit in a backpack.
• guns lend themselves to guerilla actions, becuase of their independence of supply of constant energy. Aliens may be hesitant to mess with a people who are trained in the Swiss tradition of 2 years service then keep your rifle at home. Add to that keeping them with 2000 rounds of ammo, and you have a potent trap.

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A combat rifle right now weighs about 6-8 pounds. Modern materials could cut this in half, but a good chuck of that weight is the breach block and barrel. The requirements to make this out of much lighter material are daunting, but plausible using a combination of graphite, ceramics.

Answer 26

It could be that the precursors to gunpowder were not found on your aliens planet. So they only found it on other planets but by then they had already developed other tech so didn't see the point.

If your aliens don't like especially loud noises then they may shy away from gunpowder.

Finally it's just really cheep for us to produce guns and ammo as compared to the power packs that the aliens use.