When I was doing a Knifemaker tip video fro Instagram about how I drill my handle scales, everyone seemed very interested in the pins that I used when I drilled the handle sets. I know offer the pins I use for purchase.
The size you order is the size it will be. The manufacturer states the diameter tolerance is ±0.0002″. These are hardened dowel pins that are 50-58 HRC so you don’t have to worry about them getting a ding in them too easily.
The 1/8″ pins are made with a black Delrin material and the 3/16″ and 1/4″ sizes are brown canvas Garolite (Generic name for micarta).