No one knows within a thou of what bore diameter you have and it's easy enough to correct for without slugging anyway, just use .358 bullets; if you have that size all will be well. But, if your bore is smaller all will still be well, the bullet will be precisely the "right" size when it has traveled its own length anyway. Slugging a revolver is not as easy to accomplish as it may seem (without bore damage) and it can be difficult to measure the slug within a thou without a high grade micrometer as well.
Heavy charges will allow for lead bullets to be slightly undersized because accelleration WILL force them to slug up (obturate) to bore size when fired. But, light charges won't force obtruation so we have to make sure the bullets completely seal the bore before they start or leading will be awful.
As a side issue, you need not be concerned about the safety of using a larger than bore size bullet. Even the hardest lead bullets will easily swage down the small amount needed. Not only will they size down easily your wad cutter powder charges will be so light there's no way the pressure would become excessive.
Last edited by wncchester; January 28, 2012 at 10:16 AM.