Lead is the most common metal used in bullets for a number of reasons: cost, malleability, expansion on impact…and of course density. The more weight you can cram into the projectile the more energy you can deliver downrange. The relatively high density of lead means you get a lot of bang for your ballistic buck. But when you absolutely positively need to pierce some thick armor, depleted uranium is the better choice.
For reasons I don’t understand, depleted uranium has the odd property that it “self sharpens.” In other words, instead of mushrooming on impact like lead, some of a depleted uranium projectile shears off and another super sharp tip is created underneath. The parts that shear off are extremely flammable and tend to ignite.
The vast majority of depleted uranium ammunition is produced in the 30mm variety, for use in the A-10 Warthog’s main gun and 25mm for the Bradley Fighting Vehicle or LAV-25. But it seems that a small batch of depleted uranium projectiles were manufactured in 7.62 NATO, too.
From Cartridge Collectors‘ NATODave:
The feasibility of a 7.62mm DU flechette cartridge was explored by the Air Force Armament Laboratory in the late 60’s. The final version consisted of a 28.5gr DU flechette with a lightweight plastic sabot loaded into a standard 7.62x51mm case. Velocities in excess of 4000fps were achieved. Interestingly, concerns were expressed about in-flight ignition due to aerodynamic heating although this did not appear to be a real world problem. The details can be found in AFATL-TR-69-53 dated April 1969.
Those worried about radioactive exposure should take comfort in the fact that a garden variety banana is probably more radioactive than these rounds. Uranium emits only alpha particles, which is a form of radiation that’s easily stopped by a single sheet of cotton cloth or a paper cup. Any radiation emitted should be contained by the cardboard box they’re shipped in.
But should you actually fire any of these rounds you may want to keep your distance — inhaling the radioactive dust left over from the impact could cause lung cancer and other nasty side effects.
According to some sources, boxes of ammunition have occasionally been seen available in the United States for roughly $400. And boy do I want one. Not to shoot — just to have.