One last UDS paint question

I had my drum sandblasted and when I picked it up, I cleaned it, first with a dry lint free cloth to remove excess sand, then with the Dupli-Color degreaser. It had plenty of "tack" to it which I left on deliberately to give the Dupli-Color primer something to adhere to, and after 2 cans of the primer, it's curing per the instructions. It looks good so far but it also has some rough spots on it. Spots where the paint isn't peeling per se but looks somewhat stringy and rough.

I should probably just leave it as is, let it cure, then apply the color and clear coats and be done since the drum will just wind up getting dirty anyway, but how do folks get smooth looking paint jobs when the primer/paint needs a rough surface to stick to? I could take some 220 grit sandpaper and try lightly sanding the rough patches but I hesitate since I don't want to remove too much of the primer. Was just curious in case I have go back and redo anything.

Thanks for the advice. I've picked up 2 scotch brite pads at Ace (the regular green, store didn't have the red), so I'll try those. The primer is already dried and has to cure for 7 days but I'm following the Dupli-Color instructions, practically exactly and not mixing paints. I'll learn as I go.