With typical web thicknesses, there is ususally enough room to align pins ,if you so desire, with a swamped barrel. This may seem insignificant, but with forestock moldings such as a cove and bead, it looks pretty crummy to have a pin fall right on the bead. With very thin webs, there may not be enough room for alignment. If you start with a good plane at the top of the stock, just measure down from that the appropriate distance.