I have shot literally thousands of powder coated bullets, mostly .38 Spl., but also in .44 Spl., .45 ACP, 9mm, and .38 Super. Powder Coating has several advantageous features.
But, there is one unfortunate limitation. That limitation is the process of powder coating precludes effective heat treating. However that problem is limited to those loads that shot at higher velocities. Some casters may not be aware that too soft of a bullet shot at too high if a speed, changes shape (presumably effecting accuracy). For example, if you shoot a too soft of an alloy bullet at too high of a speed, the bullet "slumps" and what was a round nose 9mm becomes a bore-size wadcutter.
I experienced that with a .44 Magnum back in the early seventies with a Lyman 49421 "Keith type". Experimenting with "pure" lead, I found spent bullets with rifling marks on the ogive of the bullet where none should be.
Now, I anticipate posts from cast-lead bullet rifle shooters who are going to claim that they have achieved excellent accuracy coupled with very soft powder coated bullets... that is not what this post is about. It is about my observations.