Since the introduction of practical, militarily significant infantry body armor, armaments manufacturers have been working to defeat it. Submachine guns firing pistol rounds have been displaced by Personal Defense Weapon calibers, and the fairly light assault rifle rounds like 5.56×45mm and 5.45×39mm are being phased out in favor of harder-hitting projectiles in the 6mm range. Given the glowing reports of the near-magical effectiveness of depleted uranium projectiles, is this being at all considered for rifle rounds intended to defeat body armor? Is it a matter of cost or is DU more problematic than at first glance?
Well, the stuff is apparently pretty toxic:
To put it in other terms, a fist will not penetrate body armor but the same amount of force with an ice pick will.
Additionally:
Stranger
I was wondering if the supply of DU is limited by the amount of uranium enrichment serving the nuclear industry, that there simply wouldn’t be enough for billions of small-arms rounds.
The main benefit of DU rounds is how much kinetic energy they can deliver. So it wouldn’t be enough just to make DU bullets, there would need to be more propellant, which would require a sturdier barrel, and all sorts of other stuff.
As mentioned above, you don’t need higher energy to defeat body armor, just more concentrated force. Sad story from a friend of a friend, but some young soldiers once demonstrated this with an ill-fated bet. A Kevlar armor-wearer insisted that the flak vest he was wearing would stop a knife thrust to the center of his chest. He lost the bet in the most tragic possible way.
It is less toxic than lead Depleted uranium instead of lead in munitions: the lesser evil - PubMed
Not necessarily. Armor piercing rounds with tungsten or tungsten carbide cores exist, and tungsten has a similar density to depleted uranium. Those rounds can be put through standard weapons without modification.
I thought “armor piercing bullets” handled that. In any case, I really, REALLY don’t want to see thousands and thousands of expended radioactive rounds all over the place. 
Armor piercing sabot rounds need highly dense and very hard materials to be maximally effective. Tungsten is the third most dense element, and is also extremely hard, and relatively common. That’s why it’s often used in APFSDS rounds. But it’s not super-common and is extremely brittle and hard to machine.
However, depleted uranium is nearly as dense, much easier to machine, and has a couple of other properties that make it great for armor piercing projectiles. First, it’s self-sharpening. Some property of the material mean that it basically keeps itself sharp as it penetrates. Second, it’s got what are called pyrophoric properties, which means that once it has penetrated, the pieces tend to catch on fire spontaneously and set everything else on fire that they touch. And to top it all off, in the Cold War US, depleted uranium was essentially industrial waste that didn’t have much value beyond being used for relatively boring things like really dense weights for things like airliners.
The combination of all that means that while tungsten is extremely good, DU is better still.
But that’s in tank shells. Body armor operates in an entirely different and much lower regime of energy, and penetration doesn’t really have much to do with the density, as much as just shape and force.
Right but they weigh about the same as regular ammunition because it’s just a tungsten core with a thicker jacket, because tungsten causes more barrel wear, and the benefit is more about the hardness than the weight. Tungsten is actually denser than DU, so DU wouldn’t offer any advantages there. It’s also more expensive than DU.
DU is advantageous when you buy it by the ton, for applications that need to put hundreds of pounds per minute downrange, and the kinetic energy is more important than the hardness. Body armor penetration is just a different application.
I can’t see why depleted uranium would be any better than several other elements of similar density and hardness. Tungsten or rhenium, for example.
U238 isn’t particularly radioactive, and that doesn’t matter at all in this application. I suspect there is a certain amount of ‘magical thinking’ going on in those reports?
DU is also difficult to machine because of its pyrophoric properties and hardness. Requires separate facilities and equipment (machined under an oil bath for starters). For the quantities (millions of rounds); just not practical for small arms. The US liked it for large caliber tank rounds (105mm and 120mm), 30mm rounds for the A-10, and some specific niche rounds for the penetration and incendiary properties.
The US (I helped for a couple of days) expended some energy to recover penetrators and any large fragments of same after Desert Storm. Tyvek suits and masks/gloves required. The Iraqi T-72s and other armored vehicles were easily penetrated and in most cases, through and through. The projectile/penetrator shape was highly classified at the time (drawing showing dimensions and characteristics was SECRET). I don’t remember health benefits to the local inhabitants as a major concern at that time.
The US DU was very inert with health concerns related to spalled or shaved off particles being ingested (don’t lick the penetrator) or inhaled. Soviet use was a bit more dangerous. One of their small air-to-air missiles had a DU encased warhead. My friend discovered a cache left behind by the Soviets at Kandahar, Afghanistan. Conveniently had the RadHaz sticker on them. I’ve got pictures! Notified higher HQ; a plane was dispatched with a team of guys (no uniform/visible ID) who disassembled the missiles and took the warheads back for analysis. He, later, I had the disposal task for the remainder. Much later in Desert Storm II (a poorly rated sequel), we came across a much larger batch at Objective Arlington and surrounding airbases. I reported but not as much excitement about retrieval (they’d get around to it). I was cautioned to segregate the quantities in separately spaced stacks, no more than a dozen in each, to reduce any radiation hazard. Good times.
Oh, it’s not easy, but it’s easier than tungsten.
From what I understand, most of the issues with DU aren’t with radioactivity, since it’s mostly U238, and is less radioactive than naturally occurring Uranium. On top of that it’s an alpha emitter, which is relatively easy to mitigate.
But it’s a heavy metal, and like some of them, it’s very toxic. Think about the uproar if someone fired lead, mercury, or cadmium rounds? It’s basically the same thing with DU.
Presumably a radon hazard if stored in an enclosed space? Or is the half-life so low you’d wait decades before much daughter products built up? ETA: for that matter, when refining uranium for nuclear purposes you’d want to remove all the radium, polonium, etc. so what do they do with it?
The standard SS190 round for the P90 with a steel penetrator and an aluminum core will go through a Level IIIA Kevlar vest at 200m. FN 5.7×28mm - Cartridge types.
This. The OP is essentially looking to use a sledgehammer to kill ants.
U-238 is radioactive, but only in the most strict sense. It’s half-life is 4.5 billion years, which means that it’s not very radioactive at all, as such things are reckoned.
Another anecdote from my mind’s wayback machine. I’m at Seneca Army Depot, early 80s. First shipments of 30mm DU rounds coming in. 588 rds. in a CNU-309* container, two containers unitized together (big metal boxes). The initial guidance is to park the incoming trailers, doors opened, in the suspect trailer area (with guard). After one hour, we were to inspect the interior for radiation leakage (existence?) with our AN-PDR something (it WAS a long time ago). With radiation meters, you have to get a background reading (zero the scale sort of) because RADIATION IS EVERYWHERE PEOPLE!!. Turns out that the SUN is a big source of radiation; who’d a thunk it! So, saving you the suspense, zero in the trailer. Next, take to the inspection bay, remove container top, leave opened for 24 hours. Next day monitor for radiation in the container. You would be surprised how much RADIATION is put out by fluorescent lights! The ammo in the container - zilch. Those requirements lasted about 3 months until cooler (saner?) folks prevailed and stopped the nonsense. Again, please don’t lick the projectiles especially if the paint is scraped off!
*yes, I had to look up the container number. It WAS 45 years ago.
The density and the shape of a round would certainly help in penetration, but the weight of the rifle required to fire it (remember, greater mass by definition equals greater recoil), the weight of the ammunition itself, the amount of powder and the required chamber pressure to send it with enough velocity… you’d need a tank. Which is why tanks and aircraft are the ones that use DU rounds to begin with. They certainly wouldn’t be wasting rounds on a single person, and if a person catches a round no body armor is stopping it.