In a (relatively) near future setting, several factions scramble to militarize as civil unrest on their planet turns into civil war. Factories are reprogrammed and prototypes sent to the front, guns blazing, in an effort to preempt the opposition. Without a large stockpile of ammunitions, however, those guns are about to run dry. How do we prevent that?


A typical "heavy armor company" consists of 3-5 large vehicles (for the sake of this question, let's say two main battle tanks, one heavy artillery and a recon aircraft) with an individual mass of up to 120 tons, supported by a convoy of transport and engineering vehicles, a few drones, power armored infantry and lots of support personnel.

The company has the ability to perform extensive repairs and/or modifications, provided that spare parts are available. Anything but minor repairs requires a hangar and some stationary equipment (think airliner maintenance). However, vehicles can be refueled and rearmed in the field, if necessary.

New vehicles, weapons and spare parts are made in large factories and sent to the front via convoy. However, since production cannot keep up with losses, most companies rely in part on field salvage and black market trade to remain operational. Vehicles are fairly modular, so removing e.g. a capacitor bank from a wrecked tank and installing it in your own is possible.

In a pitched battle, a single vehicle can use up to five or six tons of ammunition, hopefully taking out multiple targets in the process.

Notes on available technology:

  • Most vehicles above 20t carry a miniaturized nuclear (or similarly effective) power source.
  • 3D printing, advanced materials and limited nanomachines exist.
  • Rapid iterative design is common in the production of vehicles and other high tech goods, which increases flexibility and design quality, but may limit output.
  • In addition to conventional weapons and railguns, directed energy weapons and electronic warfare are effective tools in combat.

Factors that make ammunition more scarce:

  1. This society is already pretty good at making (civilian) vehicles. They've just started producing weapons and ammunition on a relevant scale.
  2. Point defenses and active protection systems are very common, so a single shell or missile is likely to be deflected. To stop a tank, you fire volleys.
  3. Anti-air and anti-orbital defenses, which rely on specialized missiles and extreme velocity shells, will get resupplied before ground vehicles. Losing a few tanks is acceptable, a ballistic missile strike on your factories is not. Directed energy weapons lack the range to serve an anti-air role.

My Question

Considering the above circumstances, would it make sense to salvage and/or produce ammunition between battles or does a company have to rely entirely on supplies delivered from the factories? Would it at least be feasible to re-produce simpler ammunition types (e.g. railgun projectiles)?

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    $\begingroup$ It is a lot easier to make ammunition than a tank. I would think that you'd run out of tanks before you'd run out of ammunition, at least from the industrial output point of view. On the other hand, ammunition has to be shipped to the tanks, so it is the transportation of ammunition from the industrial base to the units in the field that is the weak link. You should reframe your question to just say: Supplies have been cut off, what can you do in the field? $\endgroup$ – kingledion Sep 14 '18 at 13:54
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    $\begingroup$ This question seems to have a big XY Problem component - the real question seems to be about how to reduce the logistical needs of a heavily-mechanized fighting force. The usual answer is not to reduce ammunition, but instead to reduce support troop requirements - simple repairs done by crew instead of mechanics, replacing cooks with pre-packaged meals, etc. $\endgroup$ – user535733 Sep 14 '18 at 14:04
  • $\begingroup$ Four MBTs and a cannon is a platoon. Four platoons + support vehicles are a company. And aircraft are sufficiently different that they're always in separate units. $\endgroup$ – RonJohn Sep 14 '18 at 14:21
  • $\begingroup$ "Civil unrest on their planet turns into civil war." that implies a One World Government. $\endgroup$ – RonJohn Sep 14 '18 at 14:41
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    $\begingroup$ "I'm not sure that would be enough to service all those vehicles." It's not the number of vehicles, it's the complexity. Modern and near-future MBTs are far beyond the rolled steel of WW2 tanks, and require rear echelons to repair them. (For example, American MBTs are designed for quick field repair of engines, but what that means is that it's designed to easily pull out the entire engine/transmission unit and replace with new engine/transmission unit. The actual repairs are done far behind the line. $\endgroup$ – RonJohn Sep 14 '18 at 15:35

A lot of assumptions are missing in this question, so the answer is actually "it depends".

If weapons are electromagnetic railguns or coilguns, then portable 3D printers could theoretically make the rounds so long as a suitable material is available to feed them (and a suitable power supply is also available). The Quartermaster might have some sort of mechanism to grind salvaged metal into the powder form for the 3D printer, and a "sifting" mechanism to separate out materials which are unnecessary or harmful to the process. As a bonus, lower performing rounds can be produced if there are shortages of the correct materials, imagine a metal "can" full of dirt or concrete, with the metal being used to provide something for the magnetic or electric fields to grab onto, while the fill provides mass for a kinetic energy attack.

If you are using conventional ammunition, then the problem is insurmountable in the field. Ammunition is a system with multiple parts, all of which need to be made to fairly high precision, otherwise you will have issues with feeding the ammunition, reliable firing and even ballistic performance of the rounds. While you "could" make it using a 3D printer, the process would be painfully slow, and require you have access to lots of different materials to manufacture all the different parts. In the time you "print" one round in the field, a factory could produce hundreds or even thousands of conventional rounds (depending on calibre etc.)

A similar calculus will be in effect when looking at other logistical supplies, from food, to fuel to spare parts.

In WWII, we saw a fairly extreme example, with the Western allies choosing to build relatively simple, rugged vehicles (like the Sherman tank) while the Germans chose to build much more complex, expensive and ultimately unreliable vehicles (like the Panther). A Panther broken in the field would need to be recovered and often sent back to a second or third line depot to replace a broken transmission (a common fault), while a Sherman was much less prone to these sorts of breakdowns, and could often be repaired in the field.

The other issue in logistics goes right back to the manufacturing. The German industry was not well organized and eventually suffered breakdowns in production and the ability to ship units to the front (much less other issues of feeling and manning the advanced equipment), while the Western allies continually built their manufacturing base to the point that the Willow Run assembly plant was producing entire B-24 Liberator bombers at a rate of 1 every 24 hours (and this was a large, 4 engined bomber). Similar production rates were happening with tanks, trucks, cargo ships...you get the idea.

It seems very surprising that your fictional nation is unable to ramp up production to the needed extent, but perhaps like WWII Germany or post war USSR you have a command economy which focused on the "sexy" fighter planes and tanks, while ignoring transport trucks and other more mundane elements of the fighting force. They are going to have to convert to a wartime economy very quickly; or else...

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    $\begingroup$ That makes a lot of sense. Regarding your last paragraph, the problem's that they haven't had large scale conflict for generations, and the situation got out of hand while everyone was still in the scheming and preparation phase. So they end up producing the, well, sexy but overpriced, overcomplicated prototypes their engineers dreamed up and scrambling to make ends meet. And yes, whoever gets there first is bound to win this war. $\endgroup$ – Ruther Rendommeleigh Sep 14 '18 at 14:55
  • $\begingroup$ Probably low tolerances? (Unless you are speaking of cannonballs in the black powder era.) $\endgroup$ – AlexP Sep 14 '18 at 16:13
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    $\begingroup$ You don't need a 3D printer to print a rail/coilgun slug. It's just a big slug. Melt the metal, and cast it. If you're using a railgun, you probably don't care too much about the composition of the metal (it doesn't need to be magnetic, just conductive). current Railguns use steel, copper, and aluminium, some with tungsten inclusions for added penetration. $\endgroup$ – Dan W Sep 14 '18 at 17:33
  • $\begingroup$ @AlexP, you need very high precision. Perhaps my wording was off, so I will change it. $\endgroup$ – Thucydides Sep 14 '18 at 22:21

The enemy gets a vote, too

When the enemy discovers you scavenging to re-use ammunition, they will promptly start booby-trapping it.

Then some clever enemy will begin seeding your scavenging areas with slightly mis-sized ammunition, so you damage your own weapons upon use.

The process of scavenging and recycling, say, railgun projectiles will require additional workforce in the most dangerous and most expensive locations possible. That workforce seems likely to increase (rather than decrease) your support requirements - all those technicians need food, security, energy, and ...thanks to the booby traps... special equipment and medical care.

Any kind of war manufacturing within range of enemy detection will quickly draw enemy attention as a high-value target, and enemy recon will immediately seek them out. Since the mass and volume of inputs to a manufacturing process tend to be vastly greater than the outputs, forward manufacturing will require many more convoys of input materials...all of which need to be crewed and protected and supplied.

Finally, there's a strategic problem: Historically, running-low-on-ammo usually means that you have outrun your supplies, and it's time to go on the defensive until your supplies catch up to your troops. Generals keep an eye on next week's supply estimates because it influences today's actions. Scavenging resources from the battlefield is great, but it seems unpredictable, and therefore prone to influence a more conservative (and longer) campaign.

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    $\begingroup$ They do this sabotage in real life by the way. There are plenty of videos, which I won't post here because of how gory they are, on LiveLeak of fighters in Syria using ammo that was sabotaged. Invariably, their gun blows up. If this happens to a mortar or rocket launcher, it tends to be fatal. Small arms tend to just break fingers when they blow up. $\endgroup$ – Ryan_L Sep 14 '18 at 16:52
  • $\begingroup$ @Ryan_L -- indeed, and it doesn't even have to be intentional sabotage to break small arms, look up "kaBoom!" for details (common particularly among Glocks with handloaded/reloaded ammo, but can happen to any firearm under the right/wrong circumstances) $\endgroup$ – Shalvenay Sep 14 '18 at 16:56

If you're salvaging and making ammunition on the front lines, you're losing.

Perhaps because you've lost the home factories or because the home factories are now on the front lines. Purpose built factories can put out ammunition at higher qualities and quantities than anything you'll be able to make do and mend at the front.

It's possible that this is an apocalyptic scale war and that everyone is losing and they're all doing this, but if it's just you and everyone else's logistics can bring supplies from home, you're losing.

It sounds like your logistics are failing. You're trying to shorten your supply lines.

Traditionally that's done by retreating, given that the other option is to run out of bullets and either surrender or die, it may be better to order the retreat.

Now may be a good time to sue for peace

If both sides are resorting to this, a cease fire may be in order before your front lines resort to throwing rocks at each other. It's generally considered a good time to end a war if neither side can afford to keep it going. If it's just you...

  • $\begingroup$ The premise is that this used to be a low-military society and, while they have a lot of know how and capacity to make vehicles, production of weapons and ammunition is something they've just started to do, and will take some time to get up to full speed. I should probably put this in the question more clearly. $\endgroup$ – Ruther Rendommeleigh Sep 14 '18 at 14:25
  • $\begingroup$ @RutherRendommeleigh, still not worth it. You'll can use more ammunition in a minute than you can make in a day by hand, even without having to salvage materials. $\endgroup$ – Separatrix Sep 14 '18 at 14:27
  • $\begingroup$ "If you're salvaging and making ammunition on the front lines, you're losing." This is not completely true. The US salvaged all its brass shell casings. And the spent projectiles will be mangled. $\endgroup$ – RonJohn Sep 14 '18 at 14:34
  • $\begingroup$ @ron - salvaged for sure. Made back into ordnance behind enemy lines?... not by anyone who was winning. $\endgroup$ – Mazura Sep 14 '18 at 18:13
  • $\begingroup$ @Mazura the enemy salvaging your spent projectiles? They couldn't salvage your HEAT rounds, and -- given that the sides weren't supposed to have much of an arms industry before the war -- you won't have APFSDS rounds in the first place. $\endgroup$ – RonJohn Sep 14 '18 at 18:35

I agree with Separatix's answer. Your armies are already in the process of losing because their logistics isn't keeping up. Napoleon is credited with saying, "An army marches on its stomach." Logistics is not a side aspect of war. It is a central aspect which permeates every decision a competent military. If your military isn't thinking this way, it probably isn't competent enough to manufacture ammunition.

Speaking of which, if you can't supply ammunition, its also highly probable that you can't provide gasoline either. Your armor is going to be stationary very soon. If you have the logistics for gasoline but not ammunition, then that suggests there's a deep rooted issue with your nation's manufacturing of ammunition. You'd have to explain why the ammunition is manufacturable on the battlefield, but not easy to manufacture at home. Something about the battlefield makes it possible.

Some ammunition is manufacturer. I have personally reloaded handgun rounds. It's a pretty straightforward process. I bought my bullets. You can make them from lead yourself, but making full metal jacket bullets requires hardware I didn't have (but a military could). I bought the gunpowder and primers. I recycled my own brass (handgun brass can be recycled a large number of times. Rifle brass starts to stretch from the stresses).

By a giant margin, the most difficult piece to manufacture in situ is the primer. This is the small cylinder of impact-sensitive explosives that sets the main charge off. The materials used in this are not fun to create. Mercury Fulminate was popular for a long time, but there is an effort to try to get mercury off the battlefield. These are typically cast into carefully shaped brass containers. Their shape is critical. They need to fit snugly into the round, and have the right mechanical properties such that when the firing pin strikes them, they explode. At the very least this calls for a full chemical engineering factory and brass swaging equipment. And some soldiers with really steady nerves -- I would not want to be anywhere near incompletely packaged primers.

The gunpowder is easier. It's only nitrocellulose or similar compounds for handguns. RDX and related explosives do appear in the larger rounds. These are nasty compounds. Making nitrocellulose, for example, calls for nitric acid, which is not something I would feel comfortable transporting to the front lines, and I don't think you could make it. So it's still a pain, but you may have some options. If everyone is using the same explosive for propellant, you may be able to canabalize others.

Indeed this is probably your best chance. If you canabalized all of the materials, you might be able to "rechamber" a round to fit your barrel.

However, this is ignoring the reality of vehicle combat. I don't know any stats about your 120 ton vehicle, but the M1A2 Abrams is 65 tons, so you're talking about vehicles on the same order as Abrams. So if you want to penetrate one with your weapon, you're going to probably need something on the order of the kind of bullet the M1A2 fires. Meet the M829: M829 cross section

This beast is going to be trouble to manufacture. It's a depleted uranium round, which means you're going to need the capability to machine uranium. That's nasty stuff to machine, especially without dosing all your soldiers with toxic uranium dust. Perhaps you could have the bullet itself be shipped from the nation, and cobble together the rest on the front lines?

3d printing may give you options, but it is as of yet unclear whether it will be the silver bullet you need. The military is very interested in 3d printing materials used in war, but they haven't yet reached the point where we can say if its feasible or not.

In the end, the real answer is going to be the same one all real armies have: "Use less ammo if you're running out!" Real armies adapt to the reality of warfare. B

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    $\begingroup$ The 200,000 duce and a halfs made for WWII were one of, if not the, most underappreciated 'weapons' of war. $\endgroup$ – Mazura Sep 14 '18 at 19:31
  • $\begingroup$ You don't need depleted uranium to make an M829. If you don't have a nuclear industry producing DU as a waste product, you can substitute tungsten, which is a fair bit easier to handle. $\endgroup$ – Mark Sep 14 '18 at 21:47
  • $\begingroup$ @Mark tungsten isn't that easy to machine. $\endgroup$ – RonJohn Sep 15 '18 at 5:06

Another problem with your question is "Factories are reprogrammed".

That worked in WW2 because:

  1. the weapons were pretty simple,
  2. factories weren't as specialized, and
  3. the US started preparing more than a year before Pearl Harbor, due to Cash-and-carry, Lend-Lease, and foresight that the US might get dragged into the war whether we wanted to or not.
  • $\begingroup$ This is maybe off topic, but the factories I was imagining work more along the lines of 3D printing, or modern electronics production. Rapid iterative design aided by "intelligent" control software and a gigantic catalogue of modular, pre-made parts. With that, going from, say, building jet engines to building missiles is mostly a question of design and programming. $\endgroup$ – Ruther Rendommeleigh Sep 14 '18 at 21:02
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    $\begingroup$ @RutherRendommeleigh the story is based in the near future... but honestly, in this world, even in the near future 3D printing won't be the high-volume low-cost panacea that many people dream it will be. $\endgroup$ – RonJohn Sep 15 '18 at 0:17
  • $\begingroup$ I don't think 3D printing will ever beat more specialized manufacturing methods in volume, but it massively increases flexibility, lending itself well to rapid development. Consider, for example, the complexity and development costs of current day fighter/multirole aircraft, versus the number of units produced. In my personal experience working for military contractors, they're more concerned about design, development and training (well, after sales) than mass production rate. Then again, my experience is limited. $\endgroup$ – Ruther Rendommeleigh Sep 18 '18 at 14:21

As others have said, manufacturing classic modern ballistic ammo in the field won't work very well.

But the directed energy weapons will be able to resupply in the field, so if that's critical to your story, make them the focus. You can have a couple different types of energy weapons w/ different power requirements & a couple available types of fuel & generators. For instance your shortest pulsing lasers can run off their own capacitor banks driven by any generator or even batteries, but something else could operate more like a particle accelerator & may require more power, so only nuclear & massive combustion power plants will drive it (you could work that into an explanation of 120ton vehicles, maybe, by making them elongated to support a linear accelerator type weapon)

  • $\begingroup$ Thank you, that makes sense. So far, the amount of power required for some weapons plus the shielding required for those power sources (and for defending against similar weapons) is one of the driving forces behind such heavy vehicles. In addition, the resulting ability to also power very effective point defense systems increases the volume of fire required from conventional weapons. $\endgroup$ – Ruther Rendommeleigh Sep 16 '18 at 8:10

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