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Which common shotgun is named by its actual bore measurement, not by gauge?

The .410.

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  1. The .410 ✔
  2. The 12 gauge
  3. The 20 gauge

Why: Most shotguns are named by gauge, the lead-balls-per-pound system. The .410 is the exception: it is named by its bore diameter. That is why it has a decimal point.

Huh, didn't know that: The number .410 is the bore diameter in inches.

The dad joke
Why did the .410 feel special? It was the exception to every rule.
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References

Answer: The .410. Most shotguns are named by gauge, the lead-balls-per-pound system. The .410 is the exception: it is named by its bore diameter. That is why it has a decimal point.

  1. Massachusetts Hunter Education Lesson 2B Firearms Basics www.mass.gov/doc/lesson-2b-firearms-basics-0/download
    (exception .410 which is a bore measurement)
    Checked 2026-10-08.
  2. CT DEEP Hunter Safety Exam Answer Key portal.ct.gov/-/media/DEEP/hunting_trapping/pdf_files/Hunter_Safety_Manual/ExamAnswerKey.pdf?la=en
    A .410 shotgun is actually a 68 gauge. True.
    Checked 2026-10-08.

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