Cast Bullets Size Specification

Standard practice is to size cast bullets .001 inch over jacketed diameter, but there is not 100% agreement on this.  Some of the sources state that cast bullets should be sized to groove diameter, others state they should be sized to chamber throat diameter, still others state to size to .001 inch under the inside diameter of the case mouth of a fired case. 

If you are using softer lead and the pressures of the cartridge are generally low, bullets of the same diameter as the bore or even slightly less than diameter will work fine because the pressure causes the bullet to compress and "swell" to the groove diameter while in the bore. 

Take your pick...