Cheetah:
I did some research on hardness of Powder Coat paint; and what I came up with is that Powder Coat may be ~ 26 to 28 BHN. I derive that from the table on Lead Hardness using "Pencil Test" as derived from this site, plus the Sherwin Williams Data Sheet on their Powder Coatings (Not able to locate Data sheets of other PC providers listing their Pencil Test Hardness).
Sherwin Williams lists their PC at a Pencil Hardness of 2H. The 2H pencil hardness in the table indicates a BHN of 26 to 28.
The full Sherwin Williams Data Sheet on their Powder Coat paints is attached as a PDF.
Attachment 98566 Attachment 98567
I believe that those who experience poor accuracy with Powder Coated soft lead, do so because the underlayment of lead is weaker than the Powder Coat, and it gives way in the rifling despite the harder Powder coat, but the hardness of the Powder Coat stops any potential leading in the barrel. Think of the Earths crust rotating over a molten core.