Eureka! Our hero just discovered the secret of time travel, but what to do with it? "I know!", he says. "I will travel back in time as far as I can and hand them a modern firearm. They will learn how it works, and they will be technologically superior and dominate the world with me as their leader!"

At least, that's the idea.

The Time Machine

The Time Machine is a rough prototype, so it is best not to travel back and forth too often. In fact, once jumped back in time enough, it's possible that you can't ever jump back forward. As a result, the hero cannot just continuously jump back and forth in time to transport a lot of modern equipment. He has one chance, and one chance only.

Furthermore, the Time Machine is able to travel through time and, contrary to the name, space. The Time Machine can pick any past date, time and location, and the Time Machine would bring the hero there. It is not perfectly accurate though, so you might end a year sooner or later, or somewhere within a kilometer of the target.

The Hero

Our Hero is a scientist, but not a brilliant engineer. While he does have rudimentary knowledge of firearms, he cannot perfectly describe what every single component of the gun does, nor how it is produced. He might be able to explain that a striker works by using a spring to propel a metal stick against the primer, which explodes, in turn ignites the powder and thus propels the bullet forward.

He is also not a chemist. He doesn't know how modern smokeless powder is made, but he did look up how old black powder was made and he is reasonably certain he could explain the process, if necessary.

Speaking of explanations and speaking about things, our Hero is also a gifted linguist and able to speak any language, old and new, to a good enough degree that he could express even more technical concepts to native speakers.

The Goal

Our Hero wants to bring any modern firearm - a pistol, an automatic rifle, a shotgun, etc. - as well as a reasonable amount of appropriate ammo - with him into the past. Our Hero wagers that he would have the biggest chance of success of dominating the world if he would travel in time further back. As such, our Hero wants to pick a gun that even a rather old - by whatever comparison - civilization could reproduce in a good enough quality.

One can assume that the Hero is patient, so if the good people of that time require a year or two to understand the firearms, that is acceptable too, as long as it results in them being able to make the firearm afterwards.

The required time is also not very important. Equipping an army takes time, and our hero knows that. So if arming an entire army with firearms takes several months or even years, so be it.

We can further assume that our Hero brings enough Gold with him - a currency that is universally accepted anywhere - should the need to pay someone arise.

The Task

• Which firearm should our Hero bring with him, and why?


• How far back in time could he go, before even the simplest modern firearm would be so technologically outlandish, that not even the most skilled scientists and engineers of the time would be able to reproduce it?

Unless he's an expert metallurgist the biggest issue you're going to have isn't in terms of producing the parts; anyone with a drill and a hand file (or some rocks that will serve the purpose) and enough patience can make a gun from a solid block of appropriate metal and therein lies the problem. Modern weapons require modern alloys, many of which are proprietary products that the character cannot know the recipe for. Furthermore the fineness of measurement necessary to make them if the recipe is known has only existed for a few decades, some of these alloys require measurements in the parts per million.

All is not lost however, you can take some weapons that are currently antiques back a lot farther than you'd think. Assuming your character knows how to make reliable gunpowder that is. You could take a Culverin back to 3300BC Anatolia and be able to reproduce it in local bronze.

Bring the Tools, not the Weapons

The hard part here is getting the precision tooling you will need done right. Rifling a barrel and pressing ammunition is pretty darn hard without the right equipment, but all the tools needed to set up a fire-arms and munitions workshop take up surprisingly little space.

Since he has enough wealth in the 21st century to acquire significant amounts of gold and build a time-machine, I'm assuming he's fairly wealthy. Although he lacks mechanical engineering skills himself, he could hire proper engineers to modify hobbyist gun making kits to rely on non-electrical power sources such as foot-pedals, and help him design weapons to the specifications of the alloys that will be available to him in the past.

Before he goes back, he should then run tests making his own home-made bronze, gun powder, ignition caps, etc. to test his ability to make sound weapons from what will be local resources.

Of note, bronze is actually a fairly good material for making firearms. A revolutionary era bronze cannon was half the weight of the cast iron cannons of the time. Steel did not really get good enough to compete with the quality of bronze as a weapon making material until the 1800s, so your time traveler should focus on bronze as his alloy of choice.

The Weapon he Makes

To dominate the ancient world, your weapon needs a few qualities that not all historical firearms could achieve. First, it will need good penetration so it can go through the shields and armor of the ancient world. This rules out shotguns, and low calibre firearms. Secondly, it will need range. To have a true tactical advantage, you will need to be able to shoot down enemy archers, slingers, and crossbowmen before they can start shooting at you. This means you will need riffling. Third, you will need a enough rate of fire that your armies will get in many shots before your enemies can close range enough to take away your advantages. Automatic firing systems might be too complicated to reproduce since you won't be able to produce high quality springs, but revolvers should be able to be produced without them.

Other considerations are that the muzzle velocity will need to be lower than modern firearms due to poor quality of gunpowder and materials, but this can be offset with "oversized" slugs. Also manual bullet press does not need to be big, and can make thousands of rounds of ammo a day; so, you can skip the ramrods and go straight to self contained munitions for ease of reloading. The hard part is going to be blasting caps since they require chemical processes that would be hard to replicate in the ancient world without an extensive knowledge of chemistry... but I'm sure your timetravel inventor could figure it out.

The final weapon will likely be a .45-60 calibre bronze rifle with a revolver chamber, that fires lead slugs.

Nothing.

No modern firearm or ammunition will pass for an ancient one. Every speck of metal and every chemical trace will make it stand out as not belonging. Worse no one is reproducing modern firearms or ammunition prior to the ~1800's and metal lathes, chemistry, and precision measurement.

Basically if they can make a firearm, they are already making said firearms.

He should bring back a replica firearm from a historical period as close as possible to the one he's trying to dominate. The precision manufacturing and metallurgy and chemistry of the time will fundamentally limit reproduction, so picking something that could already nearly be made will help tremendously.

Note that he still has his work cut out for him. Despite outward appearances, guns don't always mean you win. It takes training. In particular, training entire militaries is a very time consuming task that may require multiple lifetimes to achieve.

For a cinemagraphic depiction of this, consider the first part of The Last Samaurai. Fighting against trained warriors when you are unfamiliar with the tactics regarding how to use a weapon, nor the strategies which let you leverage it, can go spectacularly wrong.

If your time traveler is trying to alter history by introducing "modern" firearms long before their time, his best bet would be an external hammer break-action shotgun (single or double), with brass cartridges loaded with black powder. The cartridges should be a mix of birdshot, buckshot, and "pumpkin ball" slug loads. Fixed chokes, no tighter than "improved modified", recommended. That's enough to demonstrate the effect of choke on a shot column (especially if one barrel is cylinder and the other improved modified), but not so tight as to cause trouble with the round ball loads.

If he's got any chemistry knowledge at all, he can make primers that will work, brass was a known and worked metal even in ancient times, and black powder shotguns can be made with pretty primitive steel (or even bronze) for the barrel and lockwork.

With a source of cartridges, a competent smith from 1600 (possibly as far back as 1500) could build a shotgun that could fire modern cartridges. It wouldn't be a nice to fire as a modern one (heavier, for one thing), but it would work. Once they have working firearms, the advancement can begin -- they'll be effectively up to 1860 technology as soon as they can make cartridges and that gun.

Springfield Model 1861

As long as you go to a place where people have no problem creating iron swords and equipment you should be able to get them to create a (initially probably unrifled) version of this gun that works with a minimum of tools. (https://www.youtube.com/watch?v=yB5S1LufNyo).

At first your engineers (let's assume you go to India at 100 BCE and start your conquest from there https://en.wikipedia.org/wiki/History_of_metallurgy_in_the_Indian_subcontinent#Iron and elephants hate being shot at by guns) will probably turn out something more akin to the Brown Bess rifle https://en.wikipedia.org/wiki/Brown_Bess. But this is fine! You are taking the Springfield muzzle loader because it was one of the last muzzle loaders in use, so it contains all the useful features that you'd like to eventually be implemented, but even a poor copy will be very functional.

I highly recommend using minié balls as soon as possible for ammunition. These are cheap to produce and very powerful, and will have no problem punching through any shields (think the shields of the Roman empire) or horses (think Parthian horsemen). The rate of fire will be approximately 3 RPM, which means that archers will actually have a rate of fire advantage over you, and might even have an accuracy advantage too while you are still using unrifled muskets. However this brings me to the most important advantage of using muskets over bows:

"No" training required

While you are still using the brown bess version, an individual musketman would probably be at a disadvantage to say, a trained Parthian horse archer. However, training a soldier to use a musket takes weeks, training a soldier to wield a bow takes years, not to mention the costs associated with horses and the logistics required to field them.

Your greatest advantage will therefore be the size of the armies you can field. With massed musket fire, no enemy troops will be able to get close to you. Nonetheless, issuing a detachable bayonet to every troop will be highly recommended since it allows them to hold the line while the second (and optionally third) lines keep up their withering fire.

To sustain such large armies, you'll need to bring 2 additional items:

• A handbook on medicine and hygiene: before the 20th century (and even during it), most casualties in armies were caused by disease. Without hygiene, and proper training of your officers about where to setup camp and how to guarantee a proper water supply, your army might quickly have plenty of guns, but not enough people to use them!


• A book on constructing a field kitchen: The field kitchen allowed armies to cook the meals for soldiers, thereby severely reducing the amount of time spend by soldiers on foraging and cooking their food, and therefore massively increasing how far your army can move in a day. You will need to move quickly to giving other empires the time to copy your firearm design and field their own versions.