Yes there is such as thing as a powder coated 223
No I am not seeing any companies selling them in the first page or so of google.
In short, it is fairly uncommon as it is a lot more trouble than it is worth...
As I understand it it does not work well. The main issue is the pressures and velocity in rifles are generally a LOT higher than that in pistols. this means the gasses will just cut into and around the lead bases and bypass the bullet to some degree. This will also cause lots of lead buildup in your barrel. I know in the magnum handguns they generally use gas-checked bullets. A small copper cup that is pressed onto the base of the bullet to keep a tight seal.
In general, as I understand it, cast lead should be kept in the 1100fps range unless it has a gas check. Coatings like hi-tek can also help and possibly buy you another 100-200fps, but your still talking pushing the limits as 1400fps for a 223.
