# Can a world exist with large calibre guns but without small calibre guns?

I would like to construct a world where firearm weaponry is known but is only used in large calibre weapons such as gun emplacements protecting cities and large cannons aboard large ships. There are no small arms such as muskets.

How might such a situation come about? Is it even a realistic prospect?

Assume an earth like world, but with any changes required to encourage or ensure that small firearms were not present. Any proposed changes must not break the laws of nature.

A good answer would describe how a world without any firearms evolved into the world I described above and provide reasons why small arms didn’t evolve, couldn’t be used or were otherwise inoperative or impractical.

• Our own world was like this for quite some time before the advent of personal firearms. Can you just use a historical setting or do you want all our modern manufacturing techniques etc available, but no small arms? – Joe Bloggs Oct 21 '17 at 13:16
• One possibility is a defective technology of steel. Big guns can be made of bronze (and indeed this was the material of choice for some time); small guns must be made of steel. If their steel is not resistant enough, small guns might pose so much risk of exploding in the face or their users that they won't be useful. – Luís Henrique Oct 21 '17 at 14:25
• @Luís Henrique - that is a good one. Why not make that an answer? – Willk Oct 21 '17 at 15:31
• Are you sure that you want a world without small calibre guns as opposed to a world without handguns? I'm asking because actual small calibre guns became practical quite late in history, in the Modern Age. In the Renaissance and Early Modern times handguns had huge calibres, from 0.50 inches up, similar to modern machine guns or larger. (The use of black powder combined with lack of precision machinery and a short barrel required huge projectiles to compensate.) – AlexP Oct 21 '17 at 19:33
• @AlexP What I'm after is to prevent infantry or cavalry from being armed with guns (hand guns, pistols, muskets or machine guns or anything else that can easily be moved around the battlefield). I'm OK with large installations, but I was hoping to retain a more ancient form of combat "in the field" – Slarty Oct 21 '17 at 20:02

## 19 Answers

"Large guns but no small guns" - suppose that on your world no one ever discovered that saltpeter makes a dandy powdered oxidizer. Given the lack of that discovery, there's no gunpowder. Large guns, powered by steam or compressed gasses, might exist, but the use of either implies very very high pressures and massive containers to hold the compressed/hot gas. You can't lug around a giant compressed-air tank holding gasses compressed to 10's of thousands of pounds of pressure. There might even be a sort of "design war" between those favoring "steam cannon" and those favoring "air guns".

Best of luck.

• “Saltpetre not discovered as an oxidizing agent” is a possibility but I really like the steam cannon idea. I'm slightly concerned about practicality, but it would certainly not be viable in a hand weapon. I will do a little research and then ask a question specifically about steam cannons and see where that takes us. – Slarty Oct 22 '17 at 16:55
• and then there is the alcohol-and-sponge faction, that uses flameable vapor as propellant! – Trish Oct 22 '17 at 23:02
• @Slarty note that the Archimedes steam cannon myth was busted. mythresults.com/episode55 – RonJohn Oct 23 '17 at 1:00
• Your people could discover potassium permanganate, which is also an excellent oxidizer. – RonJohn Oct 23 '17 at 1:07
• @RonJohn Yes but there are other ways to produce a steam cannon other than the idea considered by Archimedes and some of these were used as weapons in WW2 – Slarty Oct 23 '17 at 1:18

Take Pere's suggestion, but turn it on its head.

Give your world a very thick atmosphere.

A very thick atmosphere requires the projectile to have much greater momentum to attain a useful range.

$$p = mv$$

or momentum is equal to mass times velocity. Similarly,

$$E_k = \frac{1}{2} mv^2$$

or kinetic energy is equal to one half times mass times velocity squared.

Every time the projectile hits an air molecule, the projectile loses a tiny bit of speed, which is transferred to the air molecule. (This is conservation of momentum.) A thicker atmosphere just means that this happens more often than in a thinner atmosphere, because there are more air molecules to hit when passing through a similar distance.

At some point, the projectile has slowed down enough that it either doesn't have the necessarily penetration power (kinetic energy), or it drops (either to the ground, or just sufficiently along a ballistic trajectory that aiming a shot becomes very difficult). This is why the muzzle energy of a weapon is a relevant metric.

Larger projectiles generally have more mass. If you can get them going, it thus takes much more to stop them. A thick atmosphere therefore affects a small (low mass) projectile much more than it does a large (high mass) projectile. Therefore, a thick atmosphere favors projectiles with large mass.

As there are limits to how dense materials can be used to construct projectiles, this leaves us making the projectiles physically larger to pack more mass. This makes small calibre firearms very difficult to construct and use.

You don't need to change your world's gravity to give it a thicker atmosphere. Look no further than to Venus, which has an atmospheric pressure of about 93 bar (compared to just over 1 bar on Earth) but a surface gravity of only about 0.9 g (compared to Earth's 1 g).

• We have such an environment on the Earth... underwater. To a first order, the drag force is proportional to frontal surface area (since once a molecule is moved out of the way you can move as much mass as you want behind it), so the solution was to design a small caliber but long projectile. – user71659 Oct 22 '17 at 5:44
• Follow up: I think you need to look at the opposite: a world with a very thin atmosphere, but with high gravity, so that the need to create lift dominates over drag. – user71659 Oct 22 '17 at 5:52
• while higher mass helps, just amping up speed helps more to get the kinetic energy higher. – Trish Oct 22 '17 at 22:52
• @Trish that would require something other than gunpowder then – Reed Oct 23 '17 at 13:41
• @user71659 Guns don't need lift. A very thin allows both small and big guns. – Pere Oct 23 '17 at 15:51

I think the best way to approach this is to remove the usefulness of small arms, notably their ability to kill efficiently at a distance. If early guns aren’t useful enough then the research required to make them useful won’t happen in favour of other military advancements.

To that end I’d suggest having some material easily available with similar properties to Kevlar, ie: able to absorb and spread the energy of the bullets (or slashing weapons) while still being vulnerable to piercing projectiles such as arrows. If everyone is wearing this material prior to cannons being invented then small arms would be fundamentally useless at their inception, while a two kilogram ball filled with gunpowder will still be able to cause major damage. That will push technological innovation away from musketry and towards other ways of killing (heavier arrows, more deadly cannon ammo), and the resulting arms race between arms and armour will ignore light firearms altogether.

If you also couple this with ineffective metal alloying to reduce the reliability of small arms you can stump firearm development altogether by basically making reliable arms too heavy to carrry. This needs to be taken carefully, as it would also change the weight of metal required for an effective cannon.

So: ubiquitous armour that can protect against bullets (preferably invented before guns) and dodgy alloying to make guns too heavy.

• If going with this, OP might be interested in my old question Could a creature evolve a biological “bulletproof vest”? The criteria in that question makes it a seemingly pretty good fit. – a CVn Oct 21 '17 at 21:34
• ... a 2kg even without a gunpowder filling causes lots of damage (and in fact, this was the primary way they were used for quite a while). Sooner or later somebody is going to come up with sabot/needle rounds, though. – Clockwork-Muse Oct 22 '17 at 4:25
• A vest that could stop bullets but not arrows? – user41674 Oct 22 '17 at 16:42
• @AytAyt: Kevlar can stop bullets but not arrows. – Joe Bloggs Oct 22 '17 at 17:11
• Note that the mentioned stab-proof vests would probably do well against arrows. The indirect reason bullet-proof vests don't stop arrows is that nobody is making them that way, because nobody is bothering with arrows. – MSalters Oct 22 '17 at 19:46

The hard part of guns is metallurgy. This is true of both cannons and muskets, so simply having poor metallurgy isn't enough to explain this.

However, if there was an alternative source of large-calibre cannon technology (a tube strong enough to contain the blast), then metallurgy wouldn't be needed to explain it. Instead, the fact that the alternative source provides only large calibre bores, and not small calibre bores.

Imagine a plant that generates a ridiculously strong tube, like a super-strong tree where you can bore out the middle.

The super-strongness of the tree or plant might not develop until the plant is of a certain size. Small arms cannot be grown this way, while large caliber weapons can be. Possibly the Fiber structure of the tree doesn't permit cutting smaller bores out of the larger cannon and have it still remain strong enough.

Possibly these plants are bred to be stronger than they used to be, with metal-doped soils and special breeds. Over time, the plant has gotten both stronger, and smaller versions have been bred. But they are still a long way away from being able to create a human-portable firearm.

You can throw a bullet through air but you can't throw a dust particle, because bullet inertia and drag (or air viscosity) scale differently. If people in your world are small enough -let's say, one millimetre tall or less- bullets from hand guns won't have an useful range, but they can build enormous guns -1 mm or 1 cm calibre- with a range large enough to be practical.

• I love this answer. It would also add many more fascinating facets to the story. Great answer – user41674 Oct 22 '17 at 16:46

## Metallurgy fail

Make it so that your world doesn't have the metallurgy to produce small-arms-sized barrels of consistent quality and reliability. The barrel of a small arm needs to be relatively thin and light, compared to the barrel of an artillery piece, in order to make small arms workable. As a result, it's less tolerant of metallurgical defects: a given size defect is going to have more effect on a musket or pistol barrel than it will on a cannon barrel, where the the ample amount of metal around the defect will minimize its impact.

Furthermore, even a flintlock or wheellock action on a firearm requires the ability to produce small, reliable parts that work against each other in motion. While matchlocks do not need parts working against each other, they are highly limited by the need to keep the match burning, which makes concealment impossible and limits their use in damp conditions or around powder-stores. However, match is much more viable in the context of artillery cannon, where conditions are better controlled.

In addition to Joe Bloggs answer: consider making your artisans unable to craft small, precision parts. Maybe their current techniques aren't enough to craft, for example, flintlock mechanisms on muskets or make a long cave barrel.

Maybe there were some attemps on making some heavy, cumbersome prototypical muskets, but they were so bad that nobody cared to improve them. Make archery and other long-range fighting methods widespread: consider that almost everything is faster than reloading a musket... especially if you don't know how to seal cartridges properly (maybe, again, because you must be very good at crafting small components).

Without cartridges, muskets are usually loaded from the muzzle - gunpowder must be poured inside, followed by the bullet, and then pressed down with a metal rod. And even after all that, the weapon can misfire (or backfire into your face, or explode, or require further care and assistance in every possible way). Make them so bad that everyone quickly loses interest in them, since an archer can reload faster and doesn't risk the bow tearing his own face off.

If you can't craft a musket, it's unlikely that you will ever produce guns.

Make every artisan in the world think "well, until we can't solve X, no small firearms" where X may be "the lack of a suitable metal to craft small arms", "the lack of tools to craft and refine small metallic parts" or simply "the lack of the right techniques to craft a firearm precisely".

After a while, warfare will probably push into your desired direction. Big cannons to destroy fortifications or large chunks of army, soldiers armed with bows, swords and pikes to do the close fighting.

• "consider making your artisans unable to craft small, precision parts." Artisans have been crafting small precision parts for a long time (soo the Greeks and the Antikythera Mechanism 2100 years ago). The Celts and Chinese were similarly crafting small, intricately designed jewelry. IOW, "artisans unable to craft small, precision parts" is unreasonable. – RonJohn Oct 21 '17 at 19:34
• You have a point and I surely have expressed myself badly. However, firearms and, for instance, jewelry are quite diffrent in terms of requirements, and what can be made with a soft metal like gold it might be more difficult to replicate in steel. Ofc I'm no expert, tho. – Liquid Oct 21 '17 at 19:50
• What specific function would cause someone to be just... bad at metallurgy? Evolution gave them fingers that aren't great at manipulating small things? There isn't that much iron, it's all soft metals? Maybe the atmosphere reacts with iron or carbon or something and renders it not useful? The lack of tools or techniques would just mean that they would need to make new tools and techniques, not just give up. It would help if there was something physical going on as well. I DO like the answer though, and gave a +1 – user41674 Oct 22 '17 at 17:28

Imagine the development started with big guns, and never made some leaps that would benefit handguns.

• Have big guns fire stone balls instead of iron balls. (Why? Perhaps metal is several times more expensive than in the real world.) Scaling those guns down would find a "natual limit" at the size of a swivel gun, not a handheld gun, because of the expense of small, round stone bullets.
• No locks other than cannon locks fired by a linstock or matchlocks. Perhaps the metallurgy isn't good enough for springs. Not much of a problem for big guns, but again the designs don't scale down.
• Most big guns are breechloaders with removable chambers. They are less disadvantageous for big guns than for little ones.

The situation might be ripe for an inventor with lots and lots of breakthroughs. Why, let's build a smaller gun and cast our bullets from lead. Lead bullets and handguns go hand in hand, either one invention is useless by itself. But stodgy, tradition-bound master gunsmiths will insist on one change at a time -- they despair at mass-producing .50 stone bullets, or firing lead roundshot from their 24-pounders.

• In fact, on Earth the early big guns fired stone balls. – David K Oct 22 '17 at 23:30
• @DavidK, that's what inspired the answer. See the first of my wikipedia links. – o.m. Oct 23 '17 at 4:57

"Is it even a realistic prospect?" No, because cannons started as small-bore hand-weapons. IOW, you start small, with small amounts of powder, and then move up in scale as your metallurgy gets better.

https://en.wikipedia.org/wiki/Hand_cannon

Here's one from 800 years ago:

Reduce the effectiveness of gunpowder.

You need a big quantity of powder to produce an explosion big enough to propel a bullet.

Personal weapons become too heavy, so they are used only in fixed positions.

In fact, in Europe some of the first "muskets", the culverins, were small falconets (cannons) that people carried even if they were very heavy.

A strict (samurai-like?) code of honour which requires one-to-one combat and forbids shooting at humans, and the only non-human adversaries to defend against being giant-sized monsters would, in my opinion, be the best explanation.

Heavy, really heavy, wind might be a reason. As in, a planet where what we call a storm is the normal condition on a sunny day. Larger calibers would due to their mass be less affected by side wind.
On the other hand, of course, on such a world, the air would be naturally filled with deadly "projectiles" all day, every day, and nobody would need weapons to kill someone. Just wait and watch.

The inability to build sufficiently high-pressure barrels/chambers would also provide a reason, but this seems rather unlikely.

One could think about stealth being a major factor as well, firearms for some reason being used exclusively with suppressors. However, using a suppressor only really makes sense if the projectile is subsonic. Which means that in order to transmit the required energy, you need a projectile with higher mass. The length of a projectile is limited by practical means, and a mostly cylinder-shaped object's mass only grows linearly with its length (as opposed to quadratically to its diameter). Thus, calibers would necessarily be larger.
This would, however, not explain why small calibers don't exist at all.

Within reasonable bounds, and disregarding stealth, small calibers are always better. The projectile's momentum and thus the gun's recoil grows linearly with either speed or mass. However, the projectile's kinetic energy grows linearly with its mass but quadratically with its velocity.

Naively thinking, a smaller caliber would magically make more efficient use of the charge's energy by accelerating the projectile to a higher velocity. That is indeed the case with something like a bow, crossbow, or a railgun. Not so, however, with firearms. The reason is simple: Although the projectile's mass goes down with its caliber, also does the surface of its cross-section at the same rate, and thus the force acting on it (assuming equal pressure in the chamber). With e.g. a bow, the force indeed stays the same whether a stronger, heavier arrow is shot or not. Thus, physics require that the lighter arrow gains more velocity (and thus kinetic energy), and less energy is lost to the environment.

Notwithstanding the fallacy in the previous paragraph, a smaller caliber can easily be accelerated to a much higher velocity given a charge that creates, and a chamber that withstands, a higher pressure. The charge is no issue, the limiting factor is the chamber.
This provides higher kinetic energy with the same or lower recoil, and better ballistic performace (more velocity at distance, straighter trajectory).

For a real-world example, .440 Cor-Bon performs better than .50AE with much lower recoil. Similarly, .416 Barrett performs superior to .50 BMG (not in terms of muzzle energy, but at a realistic shooting distance), although the projectile only has slightly above half as much mass, and the charge is noticeably smaller, too.

The best and simple way is to anticipate the research of fiberglass/carbonfiber/plastic-polymer/ceramic in your world age (this would be possible in a pre-industrial society) that are used to build armor with compound materials. This kind of defence is very good versus cutting weapons or tiny firearms.

Basically if you include that in your storyline all handled-ranged weapons will be near to be useless. Only cannons size weapons are good enought to kill people.

The only problem might be that even white weapons would be useless, but i think that a carbon fiber or ceramic blade could be good enough to penetrate a composite armor. In any case, piercing and crush white weapons (hammers, axes and pikes) would be the favorites in war development industry as suggested in the following link: Would-a-sword-made-out-of-carbon-fiber-be-effective

In particular hammers can be made by "standard" steel (so less expensive than ceramic/C.F. blades) and break bones without the need to penetrate the composite armor thanks to the shock wave effect done by the hit.
This allows you to have a simple infantry army with effective weapons to body-to-body combat and cannons which protects cities or ships.

Another useful link: Could-a-carbon-fiber-blade-cut-the-way-a-steel-blade-could

Metallurgy: Their metal is weak (perhaps due to impurities they don't know about) and thus you need more of it to contain the blast of a gun. While you could make a small caliber gun there there's simply no reason to because it's too heavy for a soldier to use.

Your world has no explosives, or at least none useful for launching projectiles.

So how do cannons work? By steam power! You can create large emplacements on battlements and ships with boilers and steam (or other pressurized gas) tubes but no such thing as a personal/portable boiler. The steam builds massive pressure behind the projectiles which are then released via a latch in the barrel. This is not too different from how "spud cannons" work.

In a scenario like this there is no need for the projectiles themselves to be explosive. Provided the projectiles have sufficient weight and velocity they will hole ships, tear sails and snap masts (especially combined with chains) and break down stone walls.

As an added bonus they wouldn't be terribly effective against infantry which may be useful for your setting. On the other hand if your science level is high enough then steam-powered emplaced machine-guns wouldn't be unrealistic either (this was actually the case in the Riverworld books).

• – a CVn Oct 22 '17 at 7:02
• Air guns work without explosives (something like the Girandoni can be filled with a hand pump and is potentially deadly at short distances, even if its not a terribly robust weapon), so "no explosives" alone would not be sufficient to prevent hand guns. – Eike Pierstorff Oct 22 '17 at 8:18

As others have stated, include some environmental reasons that limit the effectiveness of small-arms: a lot of the naval battles during the age of sail used the ship's main cannon, and slashing weapons (knives, axes, cutlass) during boarding action, where the reload time of pistols and muskets limited their close quarters effectiveness. If your world was predominantly water-based this would be possible. Similarly, make airships as the main mode of transport; cannon and aircraft guns would be used to destroy an airship, while boarding actions may use crossbows, or slingshots with rubber ammo so as not to damage the gas cells.

What about making them technically feasible, but heavily discouraged? Imagine a world where owning and carrying firearms is completely prohibited. Something similar to several periods in Japan's history where swords were banned would be a historical precedent: Sword Hunt. Despite the ban on civilian weapons, large corporations are still permitted to arm their merchant and warships to limit piracy or raiding by rival companies. Raiding to sink is legal, but boarding and pirating goods is banned by international and corporate treaty: small-arms become technically possible, but redundant.

Alternatively, go completely the other way: laser guns may be practical for handguns but don't scale properly, so the big guns still use gunpowder.

The atmospheric conditions are always very wet or damp so things like black power get soaked and stop working. The only way of stopping this is to house them in large water tight turret like enclosures where the loading can be carried out in the dry. This is not practical for hand guns.

Potassium nitrate and sulphur are harder to come by compared to our world and tend to occur in dilute forms that need concentrating and also tend to contain more impurities that are harder to separate. This makes the process of making gun powder a lot more laborious and costly. Consequently firearms development is slow and when it does occur, gun powder is reserved for big gun prestige weapons and is not “wasted” on common soldiers and hand guns.

Glass is the only die-castable solid material available to the inhabitants.

You mention an Earth-like world. Small firearms of Earth have been historically possible because of iron metallurgy, as pointed out in other answers. That has been possible because iron is the fourth most abundant element in Earth's crust -- approx. 5% of the composition. (And to a lesser extent because aluminum is the third most abundant element at approx. 8%, although it is not used to make the primary components of small arms such as chambers and barrels.) If your Earth-like world had a different crust composition due to a slightly different planetary evolution then it would be possible that there could be no significant sources of metallic elements such as iron, aluminum, magnesium, etc., in the crust, or at least none reachable by non-metallic machinery from the surface. That would greatly limit the availability of materials suitable for machining and machinery, with one notable exception: glass. The primary component of glass is silica, which is composed of oxygen and silicon, the first and second most abundant elements of Earth's crust.

It is conceivable that a machine making civilization could evolve using only glass as its primary industrial material, aided by the fact that glass has a melting point achievable by burning organic materials and that it is easily die-cast for mass producing high quality machine parts. It also has some useful qualities with respect to gun manufacturing. It is rigid and corrosion resistant, both needed for gun barrels in particular. But it would suffer from noteworthy flaws as a pressure bearing material, namely its low resistance to mechanical shock (brittle) and thermal gradients, making it problematic for gun chambers and barrels.

So, it seems unlikely that explosive nitrates would be usable as projectile propellant as they are on Earth. For example, commonly used nitrocellulose has a pressure wave velocity of around Mach 21, 1.6 times the speed of sound of glass, and an ignition temperature of 170 deg C. Propellants with lower detonation velocities and lower gas temperatures would be required to avoid destroying the weapon itself.

The problem would be there are few practical gases that meet that criteria. This author knows of only one: steam. It's pressure expansion velocity can be easily regulated and it's temperature is within the range of known glass thermal shock limits.

Therefore, in a world where glass is the most practical machining material, guns that use gas to propel a projectile through a barrel would be limited to devices that are attached to steam sources. That would seem to preclude small caliber arms since they would simply be impractical. They would make more sense for large steam-powered cannons or mortars used to fire relatively large projectiles such as bombs, grenades or potatoes. Google Holman Projector.

It depends what you want to use the gun for.

Early hand guns had short range, poor reliability, and terrible accuracy, and (for muzzle loading guns) a very slow firing rate. Even in the 19th century, "don't shoot till you can see the whites of the enemy's eyes" was a practical piece of advice, not just a demonstration of bravado! Early hand guns were not a very efficient way to kill people.

On the other hand, dropping a cannon ball, or grape shot, into a fortification was a very good way to kill or injure many people with one shot. Even minor injuries that temporarily immobilised people could have a big effect on the enemy's ability to fight back, Given the primitive medical practices of the time, killing the enemy slowly from wound infections, etc, was just as effective in the medium term as killing them quickly.

And you might be able to use the same cannon to blow holes in walls and doors as well, not to mention destroying wooden bridges, boats, etc. Those uses didn't require high speed fire, or high accuracy.

This was the case at first. There were cannons, and later big rifles, but no small guns until way later. Just make it so small guns weren't strong enough the first time they were made so everyone stopped researching them and doesn't want to take the risk of putting money in new research about small guns