[badlucklottery]

Solid copper projectiles are the primary leadless solution on the market but they're much more expensive than the traditional copper jacket over lead core construction.

There's also solutions like Federal Syntech (https://www.federalpremium.com/handgun/syntech/) that doesn't get rid of the lead but fully encapsulates it to avoid the airborne lead problem.

[keepamovin]

It’s pretty interesting how the deformity and thermal properties of the metal would affect ballistics. I guess silicon is too brittle even though it’s cheap and plentiful and aluminum is probably too light.

That poly is also interesting. the R&D they would’ve had to do to discover a polymer that would contain an exploding bullet as much as possible

[lazide]

Thermal and deformation properties of the metal have no impact on ballistics at all?

Density sure does though.

Which is why 99% of the stuff you’re mentioning doesn’t really work.

Copper is quite dense, but still not as dense as lead, which is why it kinda works. Steel is terrible (but not completely useless). Tungsten works awesome (as does silver and gold), but is cost prohibitive except for specialized applications.

[stirfish]

There's

Interior ballistics: what happens inside the gun

Exterior ballistics: what happens when the projectile is in the air

Terminal ballistics: what happens when the projectile pokes a hole in the paper.

We use jacketed ammo (lead bullet coated in copper) because, with gas-operated guns, that lead dust that gets ground off of the bullet can foul up the mechanisms. Some ranges only let you use jacketed ammo because of the lead dust.

I've had copper pellets get stuck in airguns because they didn't swage to the barrel properly.

Edit: and suppressors for air guns are often called "lead dust collectors" because the drag-stabilizing skirt on a pellet is definitely going to leave some of itself behind. A bullet in a firearm makes a lot more contact with the barrel, so there's a lot more lead to lose.

[lazide]

Yes. And that is relevant to the aluminum projectiles, etc. mentioned before?

None of what you are talking about is relevant in this context.

[stirfish]

Yes! They all behave differently inside the gun, so they all affect the ballistics. Specifically, the deformation properties affect the interior ballistics.

[lazide]

haha, no - not to any meaningful degree. Are you getting this from ChatGPT or something?

Jacketing is convenient for encapsulating lead, but you can run gas checked hard cast at generally the same velocities without any real issues. In that case the gas check is due to coppers higher melting/vaporization point. They are more expensive to make however, and finicky, which is why you don’t see it in production bullets.

The ‘copper’ pellet you mention was almost certainly not actually fully copper, but rather copper washed lead. But you can have lead harder than normal copper (heat treated hard cast is extremely hard and ductile), and copper softer than normal lead (annealed copper is extremely soft). Most copper people are used to working with is work hardened, but it’s trivial to make it ‘dead soft’.

That also has nothing to do with aluminum or other rounds you mentioned.

If anyone even uses them, which they don’t outside of very niche cases or experiments where it shows exactly what I am referring to.

density, however, is 99% of it. including for terminal, interior, and every other kind of ballistics. BC is king. And that is something that is impossible to fake, heat treat, work harden, etc. out of.

For example, initial engraving pressure can be changed or negated by minor changes in throat, regardless of anything else. Or a coating. Or any number of other things.

there is no replacement for dense mass.

[kayfox]

In addition to Federal Syntech there is Speer Lawman, which is a bullet type called TMJ or Total Metal Jacket. Lawman has lead free primers. There is a green box variant called RHT that does not use lead in the bullets.