Gotta wrap my head around this . . so you're saying the hole in the ball itself is 1/4 reverse, and the pitch in the slug is an additional 3/16? That would total 7/16. Or are you saying that the ball itself is 1/4 reverse, but with the slug installed, it reads 3/16? With the slug installed, whatever pitch the gauge says is what you're feeling. But like itsallaboutme said, it's REALLY hard to tell the difference when there's only 1/16 difference. I'm a little unclear on what you're saying though, but either way it sounds like a screw up or a patch job by whoever drilled it. You drill the hole in the ball at the target pitch, and the slug at 0. Slug should always stay at 0. If you change pitch, you plug and redrill the hole in the ball, not drill a new slug.