Jim Stroh from Alpha Precision, Inc. provides the best advice. I've not met one respectable gunsmith (e.g. Linebaugh, Bowen, Gallagher, etc.) that disagrees with Stroh's advice. Here is the opening paragraph from his treatise: Revolver Accuracy by Alpha Precision, Inc .

"As with other firearms, accuracy of the revolver is dependent upon several factors. First, the bullet must be the correct diameter with relation to the cylinder chamber throats, and the interior barrel dimensions (the groove diameter is most often referenced, but bore diameter is important as well). When cast bullets are used, the bullet should be .0005 to .0010"larger than the barrel groove diameter. Ideally, the cylinder throat will be .0005 to.0010" larger than the bullet. To illustrate, Douglas .44 handgun barrels typically have a groove diameter of .429". The cast bullet should be .4295 to .4300". The cylinder throats should then be .4300 to .4305". Jacket bullets are more tolerant and can be groove diameter + .0010. Cylinder throats .0010" larger than bullet diameter."

I've followed this advice with every custom revolver I've ever had built. The results were always superb. This assumes that all other issues with regards to cylinder barrel alignment have been addressed.

Keith