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If I am correct, depleted uranium bullets are used because of their high weight and densitry which allows them to turn armor into Swiss cheese easily. Many modern armor piercing or otherwise heavy weapons designed for taking out vehicles, ranging from machine guns to artillery, use bullets composed of depleted uranium or comparable high-density materials.

Both sides (or at least the British) used special large caliber Anti-Tank rifles for taking out armored combatants and for hunting elephants in Africa. Of course, nobody could think of using depleted uranium at that time.

What if I combine both concepts and build a handheld rifle that fires .70 bullets at tanks? It would combine high, destructive calibers that were used for anti-armor purposes in many wars with the easy handling and reloading of modern weapons and of course with depleted uranium.

Because the gun will of course be heavy (even if short-muzzled) and the ammo will be even heavier, the gun will be designed for fire from cover or from a trench or bunker at a distance of up to 500 meters. Of course, a tripod will be included which will allow the gunner to rest while shooting.

Like machinegunners and RPG personnel, people carrying this gun might require assistants which carry ammo and protect the gunner in case of a close-range attack.

  • What do you think of my concept? Would it be plausible in a modern warfare or late 20th century setting?
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    $\begingroup$ There have been anti-tank rifles around since the second world war, although no one would really call them "hand-held". Pairing them with depleted uranium ammo is not a revolutionary step (as you've pointed out_, and their effective range was 1200 meters, not a measly 500. Basically, yes, it's very possible and feasible. $\endgroup$ – AndreiROM Jul 25 '16 at 19:59
  • $\begingroup$ Why to have tanks and antitank missiles, RPG's - if we can pack anyone with rifles with silver bullets. $\endgroup$ – MolbOrg Jul 25 '16 at 20:23
  • $\begingroup$ I'd have to double check my sources, but I remember one of the advantages of depleted uranium is not only its density but that it sheers under load rather than deforming. This has the effect of making the bullet sharper as it strikes a hardened target instead of splatting against it like lead does. $\endgroup$ – Cort Ammon Jul 25 '16 at 21:27
  • $\begingroup$ "Both sides (or at least the British) used special large caliber Anti-Tank rifles" Both sides of what? $\endgroup$ – David Richerby Jul 26 '16 at 8:38
  • $\begingroup$ You seem to be assuming that anti-tank rounds are just "bullets made of DU". They're not. $\endgroup$ – David Richerby Jul 26 '16 at 8:47
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More problems than gains

The main problem that makes your concept moot is that the human body can only handle so much recoil before the poor squishy humans that fire the weapons break. And you reach that limit far before you get any practical upshot of using Depleted Uranium (DU) bullets.

There exist sub-caliber bullets (tungsten carbide though, not DU) for firearms today, specifically for rifles. A sub-caliber bullet of high density does not pack more of a punch, but it allows the bullet to fly faster, which makes for a more shallow trajectory and shorter time to target, which makes it easier to hit. I have personally seen the Swedish military soldier handbook for sharp shooter rifles — such as the L96A1 AW — where the difference between using full caliber and sub-caliber ammunition is shown. Unfortunately I do not have it available too show you so you will have to take my word for it that the difference is quite marked.

The same thing goes — partially — for tank ammunition. Yes, it is true that the chemical / metallurgical qualities of DU are advantageous when it comes to defeating armor, but the improved ballistics of sub-caliber ammunition is also of great importance in that it makes it easier for the gunner to hit at greater range.

Anyway, back to squishy humans. You are asking: can you use DU to increase the "punch" of a weapon so that weapons that can be lugged around by humans become a viable threat to armor?

Answer: no.

DU is not a magic force multiplier. You still need to impart kinetic energy on the bullet. As this happens you will create recoil. And if you are trying to brute force your way though armor, you will create so much recoil that a human cannot handle it. This means you cannot increase the weapon's effect much by using DU.

Statically mounted heavy weapons already pack more "oomph" than your fictional soldier-carried weapons do. And then there are rocket propelled grenades, and anti-armor missiles, which do not rely on brute force but instead on clever explosives to make their way through the armor. Not to mention that missiles are guided and thus can be fired far outside the engagement envelope for your ballistic weapon. The thing is that modern armor is designed with these kinds of weapons in mind. And since these weapons pack more of a punch than that of your fictional firearm it makes your weapon moot because it does not add anything of value.

Then — as a bonus — you have the problem of the metal being slightly radioactive which will create all sorts of "fun" problems. No, not acute radiation sickness, but let us just say that having the common soldiery run around on the battlefield with fissile material will make the world community raise an eyebrow or two. Not to mention that their travels home after the war will be "interesting" when they set of airport, port and border alarms left and right.

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    $\begingroup$ +1 for the excellent logic. One might point out that ATGMs in general are relatively expensive, and that bullets are much, much cheaper. The reason that ATGMs are widely deployed is that its a (relatively) low cost and effective method to kill armor packed in a man portable package. If AT rifles with DU rounds are still viable, militaries would use those instead. $\endgroup$ – WarPorcus Jul 26 '16 at 0:22
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    $\begingroup$ @WarPorcus No, they will not. Because RPGs like the AT-4 and recoilless rifles like the Carl Gustav are cheap enough to out-compete ballistic anti-armor. There is a reason anti-tank rifles has become a forgotten obscurity. $\endgroup$ – MichaelK Jul 26 '16 at 0:33
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    $\begingroup$ DU is really more dangerous as a toxic heavy metal than as a radioactive one. Its shortage of radioactive content is what makes it "depleted", and its method of production means that it is, more or less by definition, economically infeasible to get fissionables out of it. $\endgroup$ – hobbs Jul 26 '16 at 2:57
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    $\begingroup$ Actually, your "squishy humans" aren't all that squishy. Anti tank rifles have been designed and built that are extremely large. The trick is that they were designed to be fired from a prone position, and in the largest examples, they would direct recoil into the GROUND rather than into the soldier. The soldier would basically act as a weight that keeps the rifle in position while it fires. We humans may be squishy, but we are also clever (especially when it comes to warfare). $\endgroup$ – JBiggs Jul 26 '16 at 17:29
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    $\begingroup$ @JBiggs And there you just showed why my answer is apt to the question. OP asked for weapons that are easy to lug around. As you have proven: they are not. And this was back in the 40's and 50's when armor was no-where near as advanced as it is today. Today armor is a much tougher nut to crack. Hence: man-portable ballistic anti-armor weapons are not feasible, even if you use depleted uranium. $\endgroup$ – MichaelK Jul 26 '16 at 19:02
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You are talking about the fairly common anti-materiel rifle, first used in WWI and almost ubiquitous in today's armies. They are typically .50 caliber (or the metric equivalent ~12mm, give-or-take), and are designed to be fired from a prone position using a bipod or similar stabilizing device to support and steady the weapon while the rifleman takes aim and fires; large muzzle breaks help to reduce recoil and the abuse the rifleman's shoulder takes from using the weapon.

While I don't know if they use depleted uranium per se, that's not the only core used for armor-piercing ammunition: Steel and brass are also common in that role. These rifles also often fire explosive or incendiary rounds.

By way of example, one of these class of weapons in use in the US is the Armalite AR-50 firing .50 BMG ammunition. It has an effective range of over 2,400 meters, well in excess of your desired 500m.

These rifles are largely ineffective against modern armor (i.e. tanks), however. Given how similar they are to what you describe, I believe that if it were feasible our armies would already have them; you'll instead have to rely on airstrikes and heavy artillery.

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  • $\begingroup$ I edited your metric equivalent. 100mm was quite a beastly round! 1/2 inch comes out to 12.7mm. 100mm would be nearly 4 inches in diameter, and would certainly provide some "kick" when fired! Let me know if there's any need to correct my edit. $\endgroup$ – Cort Ammon Jul 25 '16 at 21:30
  • $\begingroup$ Just a quick aside to your excellent answer: several early Anti-Material rifles fired rounds up to 20mm diameter, which is even larger than OP's desired caliber of .70. Using a round that massive is largely redundant with modern firearms, but I thought I'd confirm that such calibers actually do exist. The Finnish-made L-39 Lahti is an example. $\endgroup$ – MozerShmozer Jul 25 '16 at 21:38
  • $\begingroup$ @CortAmmon Yikes! Thanks for the correction! It was based on the mm calibers listed on the Wikipedia article, but I looked at length instead of diameter. Whoopsie! $\endgroup$ – Kromey Jul 25 '16 at 22:11
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The only possible upside for using DU penetrators in an anti material rifle is the idea that the Uranium core is pyrophoric (i.e. will spontaneously combust as it passes through armour).

This requires that the round be saboted (i.e. the DU penetrator is encased in a plastic or right metal container [sabot] which peels or drops away as the round leaves the muzzle), and that the round pass through armour plate with enough thickness that the round liquify so the drops of molten uranium will ignite on the other side. Condition one is rather straight forward (this has been mentioned in another post already), but the pyrophoric properties of the DU round will only take effect under very limited circumstances. If you shoot a person, a concrete wall or through a truck, it is very unlikely the round will ignite.

Indeed, if you want to set your target alight, there are already incendiary rounds which are designed to ignite on impact using a different process. As well, since most armoured targets are much heavier than can be reasonably be dealt with by a rifle, you might invest in a grenade launcher which fires high velocity rounds for a flat trajectory and the ability to deal with moving targets.

The Swiss ARPAD 600 used a 35mm high velocity grenade to propel a warhead out to 500m against moving targets (I can't find the source, but the range against stationary targets was probably about 1000m). From the picture you can see the weapon had to have the barrel over the shooter's shoulder in order to allow for the recoil mechanism to work. Since the grenade was only 35mm, there was a severe limit to the effectiveness, and substitution a modern 40mm high velocity grenade might not improve matters too much.

enter image description here

Other proposed weapons like the XM-307 grenade machine gun, XM-25 or the Barrett XM-109 are limited to 25mm projectiles, which should give you some idea of how large a man portable weapon can actually be.

XM-307 XM-307

XM-25 XM-25

XM-109 XM-109

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I believe you are grossly overestimating the effect of DU compared to other materials. The tungsten DM33 round penetrates 560mm of armor at 2 km, the contemporary depleted uranium M829A1 round penetrates 570mm at 2 km. Newer DU rounds will be even better, but exact numbers tend to be secret.

Yes, it makes enough of a difference to make it worthwhile in tank guns of the target are other MBTs.

No, it doesn't slice armor like swiss cheese.

So DU for sniper rifles or anti-materiel rifles might make sense if ordinary rifles cannot deal with body armor any more. It could become an issue if powered armor ever becomes a reality -- and people are already working on powered load-bearing assistance.

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If you have ever fired a truly large caliber handgun, the first thing you notice is that they kick, often very hard. The most difficult part of using one of these 'hand cannons' is the recoil shock disorienting the shooter and making target reacquisition for a second shot difficult. It is unlikely that a firearm capable of firing depleted Uxxx rounds at greater than .50 cal could be considered both handheld and effective. Bear in mind, you never want to be close enough to a tank ( or APC, etc) to be able to use a handgun against it.
A handgun is limited in the muzzle velocity it can support ( remember F = m*a) so the faster the round, the less mass required to do the same damage. In the case of high mass rounds, combining the extreme muzzle velocity with the extreme mass will require an equally extreme weapon, not likely to be a handgun, or even hand held.

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  • $\begingroup$ I suspect if you were close enough for a handgun to be worthwhile for a tank, a Molotov would be far more effective. $\endgroup$ – Wayne Werner Jul 26 '16 at 1:54
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There is modern example of 20mm rifle. And, it seems to be able to deal with recoil. The Mechem NTW-20:

The barrel along with the receiver could recoil inside the chassis frame against combined hydraulic and pneumatic damping system. Large two-chamber muzzle brake also helps to keep recoil at the acceptable level

https://en.wikipedia.org/wiki/Denel_NTW-20

gun

So caliber is handy, if the bullets aren't. Imagine made in China (not so) depleted ammunition.

And, all theese XMs (in other post) are grenade launchers not rifles so its shells do require far less speed, and latter two hasn’t ever been mass produced.

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  • $\begingroup$ I don’t understand «Imagine made in China (not so) depleted ammunition.» and how that’s not “handy”. $\endgroup$ – JDługosz Sep 7 '16 at 3:36
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Aside from the higher density, DU has one other advantage that makes it particularly advantageous for anti-armor: DU produces a huge shower of sparks when it hits metal, tending to set anything flammable on fire. This is something that tungsten, another armor piercing material, doesn't do.

If you look at some of the old videos of an A10 shooting up a tank on a range, you'll see a lot of huge sparks flying around when the rounds hit. That's the DU igniting... very effective at setting tanks on fire.

So, one possible use of DU in small arms would be producing a lot of sparks, possibly setting things nearby on fire.

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I know this is a stretch but what if you made the rifle have a free floating barrel mechanism, and instead of a conventional round use electrothermal chemical propellant, which would use electricity to turn a tungsten wire to plasma and ignite the propellant at such a high temp that the gasses would expand faster allowing for an increased velocity giving you more bang for your buck. This would then allow you to fire DU rounds in a way that would be more economical at least on the recoil side of things. And maybe you could even use mini discarding sabots, and have a smoothbore barrel and fin stabilized bullets.

Or if you are really far into the future you can fire it from a handheld rail or coilgun (assuming they have been invented) to get hypersonic ammunition velocities.

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