How to Measure Shotgun Bore Diameter and Barrel Thickness | MidwayUSA Gunsmithing

Published on July 23, 2015
Duration: 1:18

This guide, presented by Larry Potterfield of MidwayUSA, details the precise methods for measuring shotgun bore diameter and barrel wall thickness. It covers the use of specialized tools like the Skeets digital bore gauge and the Newbolt & Thorp barrel wall thickness gauge, providing step-by-step instructions for accurate readings essential for gunsmithing.

Quick Summary

Accurately measure shotgun bore diameter using a Skeets digital bore gauge zeroed with a ring gauge, then add the readings. For barrel wall thickness, use a Newbolt & Thorp gauge, setting it to a specific point like 9 inches from the breech, zeroing the dial indicator, and recording the measurement.

Chapters

  1. 00:00Introduction to Shotgun Barrel Measurements
  2. 00:13Measuring Bore Diameter with Skeets Gauge
  3. 00:34Measuring Barrel Wall Thickness with Newbolt & Thorp Gauge
  4. 01:06Conclusion and Summary

Frequently Asked Questions

What tools are needed to measure shotgun bore diameter and barrel thickness?

To measure shotgun bore diameter, you'll need a Skeets digital precision bore gauge and a ring gauge. For barrel wall thickness, a Newbolt & Thorp barrel wall thickness gauge with a dial indicator is recommended. Ensure all tools are zeroed correctly before use.

How do you accurately measure shotgun bore diameter?

First, zero a Skeets digital precision bore gauge using a ring gauge. Then, insert the gauge into the shotgun bore and record the reading. Finally, add this reading to the known diameter of the ring gauge to get the precise bore diameter.

What is the correct procedure for measuring shotgun barrel wall thickness?

Set the barrel stop on a Newbolt & Thorp gauge to the desired point (e.g., 9 inches from the breech) and zero the dial indicator. Slide the barrel breech-first over the rod, hold it against the measuring ball, and record the dial reading. Repeat for other points like the muzzle.

Why are accurate bore diameter and barrel thickness measurements important for shotguns?

Accurate measurements are critical for gunsmithing, ensuring proper fit of components, identifying potential wear or damage, and maintaining the firearm's safety and performance. They are essential for any serious shotgun maintenance or modification work.

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