Archive: August 2025

Measuring the inner bore of your shotgun is an essential task for any gun owner or sports shooter. Understanding the dimensions of your shotgun’s bore can help in selecting the right ammunition, maintaining the gun’s accuracy, and ensuring safe shooting practices. In this article, we will discuss the importance of measuring your shotgun’s inner bore and provide a step-by-step guide on how to do it accurately.

Understanding the Importance of Measuring Your Shotgun’s Inner Bore

The inner bore of a shotgun refers to the diameter of the barrel where the ammunition travels before exiting the gun. Knowing the exact measurement of your shotgun’s inner bore is crucial for choosing the correct size of ammunition. Using the wrong size of ammunition can not only affect the accuracy of your shots but also potentially damage the gun. Additionally, regular measurement of the inner bore can help detect any signs of wear and tear, allowing for timely maintenance to prolong the gun’s lifespan.

Measuring the inner bore of your shotgun is also important for safety reasons. A properly sized bore ensures that the ammunition fits snugly and securely in the barrel, reducing the risk of misfires or other malfunctions. By accurately measuring the inner bore, you can be confident that your shotgun is in good working condition and ready for use during shooting activities. Overall, understanding the dimensions of your shotgun’s inner bore is essential for both performance and safety reasons.

Step-by-Step Guide to Accurately Measure the Inner Bore of Your Shotgun

Here’s how you can measure it:

1. Gauge or Bore Size: First, determine whether your shotgun is measured in gauge (like 12 gauge, 20 gauge) or bore (like .410 bore). Gauge is a measure of the number of lead balls of bore diameter that equal a pound in weight.

2. Use a Caliper or Gauge: To measure the actual bore diameter, use a precision caliper or a bore gauge specifically designed for shotguns.

3. Insert the Tool: Carefully insert the caliper or gauge into the bore of the shotgun. Ensure it’s inserted straight and not at an angle to get an accurate measurement.

4. Take the Measurement: Once inserted properly, read the measurement on the caliper or gauge. This will give you the diameter of the bore.

5. Check in Multiple Places: For a more accurate measurement, check the bore diameter in multiple places along its length, especially if the bore is not perfectly cylindrical.

6. Record the Measurement: Note down the measurement for future reference when selecting ammunition or discussing your shotgun’s specifications.

Start by ensuring the shotgun is unloaded and remove any obstructions from the barrel. Insert the cleaning rod into the barrel from the chamber end until it touches the bore’s wall. Mark the cleaning rod at the point where it exits the barrel.

Next, carefully remove the cleaning rod from the barrel and measure the distance from the tip to the marked point using a measuring tape. This measurement represents the inner bore diameter of your shotgun. It is essential to take multiple measurements at different points along the barrel to account for any variations in bore size. Once you have gathered all the measurements, calculate the average to determine the most accurate inner bore diameter of your shotgun.

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