Gunsmiths have been using barrel micrometers like this one for decades and the instructions really couldn't be easier. Simply drop the correct Go Gauge into the previously installed barrel, slip the barrel micrometer over the tenon and record that measurement. Remove the Go Gauge, back the micrometer off, and place the included 1" hardened steel ball on the cone and record that measurement. Once the tenon is cut on the new barrel, you use the measurements from the old barrel to cut the new chamber and cone without ever removing the barrel from the lathe or screwing the action onto the barrel.
Barrel Mic Features:
- Helps you get your chamber and cone cut quickly and accurately
- Mitutoyo Micrometer Head
- Includes hardened 1" steel ball
- Specifically designed to work for Bat and Panda Actions but will work with tenon max diameter 1.075" and lengths of .75" - 1.25"
- All that you need is a "Go-Gauge" and any barrel that has already been chambered for that action.
The PMA Barrel Micrometer is a well thought out, simple, and effective tool. If your action is a glue in, or you just don't want to risk degrading the bedding by removing a screw in action, this tool is exactly what is needed. It functions to duplicate the cone and headspace dimensions from a reference barrel to your new barrel. With the barrel held solidly and the tool pressed firmly against the shoulder, we found it easy to duplicate dimensions within 0.0005" on a new barrel for a BAT B action (1-1/16" tenon).
After getting the tool, I immediately chambered a barrel for a BAT S action, setting the depth of the bevel on the back of the barrel was a piece of cake and was able to duplicate the headspace of my old barrel within .0005. I'm very pleased with this tool. Thinking about turning some blanked plugs to duplicate Remington tennons, and bolt nose recesses. It will work as is to set headspace on anything with a 1 1/16 tennon.