Hi jmill, let me welcome you with your first question...
As Andy said, you might get some flashing if your wire is smaller than your hole, but to what degree depends on the temperature of your lead.
I actually drill out some of my wires on various molds because I often prefer more stout lures; when I go back to the recommended wire sizes, there is a little over run, but this is easily cleaned off with a needle nose pliers or even my thumb nail.