The Hi Tec Supercoat Polymer coated bullets tech came from Australia where it has been used for a long time,
I am converting over to them. I have not tried any powder coated ones nor the difference as far as barrel wear. I do know that clean up is much easier and there is little to no smoke due to lack of conventional lube,
Bayou Bullets (Donnie Miculek) has good ones as does Missouri Bullets.
About Our Coatings - Hi-Performance Bullet Coatings
You casters can buy the chemicals and coat your own or the powder coating.
I would like to see some data comparing the two.