I am not sure what the law actually says but when I lived in Kansas, they told me it was OK to use my Sharps black powder rifle to hunt during primitive arms season.
The only thing the game warden wanted to know was if the components were loaded separately. I told him yes and he said it was OK.
In Ohio, you can use your BP rifle during regular deer season. So,,, if you have one that’s more accurate than a slug shotgun,,,,,,,,
in Ohio, you can use your Black Powder rifle during regular deer season