What's a caliber in guns?

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Tags

1. #diameter
2. #inches
3. #hundredths
4. #projectile
5. #approximate
6. #internal
7. #calibre
8. #shoots
9. #millimetres
10. #example
11. #thousandths
12. #barrel
13. #firearms
14. #firearm
15. #caliber
16. #measured
17. #particularly