I'm thinking of making some copper bullets and using tungsten as tip material, not to help with penetration, quite the opposite, I'm thinking it could work as a wedge to help with expanding the bullet on impact.
It would be a small tip, just like the plastic ones we see in use now, which I highly doubt would in any way replicate any "armour piercing" rounds out there.
Still, these things can be touchy subjects, and I wonder what the laws in the US would be regarding such a projectile?

In Italy where I live, armour peircing rounds are illegal, but a round that contains one of the same components, though isn't capable peircing armour, should be legal.

Still, with the irrational laws and bureaucrats, you never know...

AP rounds per se are not illegal to possess in the US.

However, its illegal for a manufacturer to sell AP ammo to the general public.

So if you did that here, on your own, and didn't sell it, you would be absolutely fine.

Our rules for what is considered AP are kind of silly, though.

I believe it is illegal for pistol ammo in the US. Most any CF rifle will penetrate any common vest, but that doesn't count.
One of those Don't ask, Don't tell things. Done in the privacy of your own home.
I would not have even asked the question; now you are on Big Brother's radar in Italy.

What I'm talking about would NOT be AP rounds.
It just sounds kinda like it if you mention "tungsten tipped" bullets. I don't belive a tungsten tip weighing in the order of 10 grains or something like that, could possibly pierce armour.

Was this the theory of the old Remington bronze point?
C

Yes.
I guarantee you that if you put a tungsten tip on a 30-06 it would penetrate any common police vest; level 2 and 3 are for handguns.
Of course, the same would happen with a nerf sponge tip too.
Why aren't you making it from something not so hard to machine? Just curious.