Geeze, don’t get your undies in a wad. I was genuinely curious about such bullets and how they solved the problems I mentioned. The idea patchbunny presented sounded promising.
As to the other thing, diamonds are freaking hard. If that lands can’t bite into the bullet, either its diameter is small enough to pass by them, in which case the bullet doesn’t spin and loses considerable accuracy, or the bullet jams. I have no cite, other than plain old common sense.
This is GQ. We don’t rely on common sense here. We demand facts!
Your objection doesn’t really stand up to scrutiny, Q.E.D..
You just jacket the diamond with copper, or use it as a hard point in a composite bullet, or use small industrial diamonds in a sintered bullet.
That part of the problem is trivial.
Fair enough, Q.E.D. FTR, I’ve been through the entirety of the texts from my two graduate classes on ceramic engineering, and not found a single reference in those works to ceramic bullets, but I have to ceramic armour, which is not the topic at hand. My reference is limited to the class notes from my professor who worked for the DoD, which is not even a source I can use a bibliographic cite from. I’ve also checked out the reference books from my other 4 materials science courses, and not found anything in there either, save for a brief mention that the “Soviet Army field-tested 20mm Si3N4 rounds” against the Chobham armour of M1 tanks. How they got ahold of samples of M1 tank armour or recreated it is not mentioned.
I’m not certain that the lands of the barrel need to “bite” as much as you believe. IIRC the steel 7.62x39 WP rounds that are very common throughout the world still work fairly well in the barrels of guns, but they do destroy the lands unless especially hardened or even (reputedly) Teflon-coated. Thinking about the mechanics of a rifle barrel, I always thought that the rifle groove guided the spin of the bullet regardless of deformation, and the fact that they “bit into” the softer metal was a side-effect or consequence of the fact that a copper or lead round was being forced at several thousand feet per second down a steel barrel - not so much that the “bite” was needed to impart the spin. Do you see what I’m getting at with this thought? That is, is it a requirement of the safe and effective design of a rifled weapon that the grooves bite into the softer metal? Because I personally honestly do not know.
FTR: I took exception to your use of the word “respectable” and you seemed to be implying that if I could not find it online, then it was not citable, and thus worthless. Maybe it is in fact worthless as a source for this thread, but not for the reasons that I’m not respectable or that it’s not online.
No, what I meant by “respectable” was just that–a Google search for “ceramic bullet” came up with quite a few online novels and other crap having nothing to do with what I was looking for.
In any case, my feeling is the lands have to bite into the bullet a little to impart spin. I don’t think mere friction will do it, though I could be wrong. Even steel jacketed bullets aren’t terribly hard, since the jacketing isn’t tempered.
I wanted to point out that Jim Butler mentioned in the Wired article was a contributing author on one of my papers. I’ll send you a reference if you want.
I have nothing more of importance to add.
how about a diamond tipped osmium slug with a discarding sabot? Heavy, stylish and practical.
I like it, krisolov. Have to define “practical” in a special way, but I like it. 
it’s no 1920s style death ray, but I think it’d work just as well…
Just confirming that there have been various calibers of ceramic bullets. I had a large stock of them at China Lake from 5.56 through .50. We even developed a 25mm ceramic round to be used as a frangible TP projectile, and it was contracted to Coors. Not only a beer maker, they have a very nice ceramic facility. The initial rounds worked wonderfully, but it was later discovered that for various reasons, they couldn’t be made in high production rates at the same quality (shattering in the barrel), so they were put on the shelf because of cost effectiveness. Eventually, sintered, powdered steel became the best method.
Everything else has been pretty much covered.
Darn it, I was hoping to suggest this! 
Would a diamond tip added to a regular bullet (adjusted to retain its aerodynamic integrity) actually help anything? Existing piercing rounds are so effective already that I wonder if there would be any point to this.
Now, when we can produce enough diamond to use it as a building material, then we’ll be talking.
<obligatory reference> Neal Stephenson’s The Diamond Age. </obligatory reference>
A diamond-tipped depleted uranium round, laminated with teflon.
Would diamond bullets have an advantage in heat resistance? That is, say you want an exceedingly high velocity bullet. Can a lead bullet survive beyond a certain velocity without vaporizing? Wouldn’t a diamond bullet be superior in this respect and thus have a greater range? Also, as I understand it, increasing velocity nets you kinetic force faster than increasing mass so our hyper velocity diamond bullet theoretically should have some oomph behind it.
Just throwing this out as food for thought.
[nitpick]
You’re correct, if you mean “kinetic energy” (not “kinetic force”). For momentum, on the other hand, velocity and mass are equally important. I think that the energy of a bullet is more important (if it were a matter of momentum alone, the kick of the gun would kill you), but there might be situations where the momentum is important, too.
Only if you can explain why TMBG would use the same title as a Mahavishnu Orchestra track from 1972.
Now that I’m home with minimal distractions, I can add a bit more. (Damn coworkers and bosses who want to chat during lunch).
Something does have to “bite” not only to give a consisent spin, but also to create a gas seal. Without a seal, you get a lot of blow-by gas that is a huge waste of energy. Ceramic core bullets are still surrouned by a softer material. A fully ceramic bullet (at least the ones that I am aware of) are set in a copper or usually, plastic sabot. In larger ammo, steel and the fully ceramic I mentioned earlier, the seal and spin is provided by the driving band, which is very small compared to the bullet and soft, made of aluminum, copper, iron, and in some cases, plastic, the bullet itself never engaging the rifling. The harder the driving band, the more work is required to push a bullet into the forcing cone, so the peak pressure climbs at an icredible rate, and barrels and gun parts wear out very quickly. Softer steels can work, but the ammo for most medium caliber ammo is actually harder than the barrels. You’d think that such a small piece of soft metal or plastic would be sheared by the rifling, but they aren’t. Recovered ammo shows a perfect cut on the bands where they swage over the lands.
A different approach is polygonal rifling, where nothing “bites” into the bullet, but the bullet or sabot is completely deformed to provide spin and seal. Without them, you are shooting a musket. Even a morter round has gas seals and fin stabilization.
Geez, I’m surprised nobody has mentioned killing Colonel Kurtz yet.
Thanks, Turbo Dog - I know you know your stuff. Q.E.D., looks like you were correct too on the importance of the lands biting into the bullet. Oi! (raises hand)
Dipped in cyanide!
