When loaded correctly a coated bullet will not lead anything. I've loaded home cast/coated bullet that were 2/1000th's undersized in 9mm semi-auto's and never had any leading. Had 9mm firearms that had bbl's that slugged .355", .356" & .357" (typical). Sized bullets .356" at 1st and when I ran out of them I switched over to .358" for everything.
This is what a 686 looks like after a 200 round range session using a home cast/coated 158gr bullet sized to .358" and 3.3gr of bullseye powder. As you can see the cylinder has very little fouling on the sides and the cases have no soot on the sides of them.
I probably should of taken a picture of the bore but I took these pictures and did a thread on another website a week earlier. This is a 1911 chambered in 9mm after a 500+ round range session with 125gr cast/coated bullets and a 25,000psi/1100+fps load.
Yes there is a layer of grey fouling in the bbl. But it easily comes out with 1 wet patch of hoppe's #9 and +/- 10 passes. Then 1 dry patch to finish the cleaning in less then 1 minute.
Coated bullets do have their limits & the limits of the bullets I cast/coat had thiers in a 308w. I cast a 14bhn bullet coated and sized to .310" for the 308w. I've used loads with 50,000+psi with several different cast bullets in that 308w and never had any issues. But when I used a 50,000+psi load pushing the bullet over 2700fps I started seeing this.
Those black streaks came out easy enough using bore-tech eliminator. Just surprised me the pc coated actually started to scorch/burn in the bbl.
Anyway been shooting cast bullets since the 80's and started pc'ing my cast bullets in 2014. Never had any leading with a pc'd bullet. It actually takes something mechanical to scrape the coating off of a coated bullet to get leading with them.
This is what a 686 looks like after a 200 round range session using a home cast/coated 158gr bullet sized to .358" and 3.3gr of bullseye powder. As you can see the cylinder has very little fouling on the sides and the cases have no soot on the sides of them.

I probably should of taken a picture of the bore but I took these pictures and did a thread on another website a week earlier. This is a 1911 chambered in 9mm after a 500+ round range session with 125gr cast/coated bullets and a 25,000psi/1100+fps load.

Yes there is a layer of grey fouling in the bbl. But it easily comes out with 1 wet patch of hoppe's #9 and +/- 10 passes. Then 1 dry patch to finish the cleaning in less then 1 minute.

Coated bullets do have their limits & the limits of the bullets I cast/coat had thiers in a 308w. I cast a 14bhn bullet coated and sized to .310" for the 308w. I've used loads with 50,000+psi with several different cast bullets in that 308w and never had any issues. But when I used a 50,000+psi load pushing the bullet over 2700fps I started seeing this.

Those black streaks came out easy enough using bore-tech eliminator. Just surprised me the pc coated actually started to scorch/burn in the bbl.
Anyway been shooting cast bullets since the 80's and started pc'ing my cast bullets in 2014. Never had any leading with a pc'd bullet. It actually takes something mechanical to scrape the coating off of a coated bullet to get leading with them.