Here is a link to a set of small bore gauges on eBay they are also available from Amazon and Enco. This should be a must have for anyone who loads or reloads. Measure from 1/8 to a little over 1/2. You just insert the gauge into the hole and open it until you feel a light drag then remove and measure over it with a micrometer. With a little practice you can get accurate readings in the tenths of a thousandth.