Got a new 4 cavity brass mold from MP Molds, and it refuses to fill out the base. Looks like a freshly seated primer in the primer pocket looks - space around the perimeter. Sometimes there is just a little lead way down in the nose section. I've preheated the mold, the sprue plate is plenty hot, I'm at my wits end. I've got nearly a dozen of Miha's brass molds and I've never run into this. Any ideas?
Don