Shotgun gauges in common use

The bore sizes given are their nominal imperial equivalent.

  • 10 gauge = .775 inch - Fairly rare now, was used for larger birds, e.g. geese.
  • 12 gauge = .729 inch - The 'standard' shotgun gauge. If you were to be handed a shotgun, chances are it'll be a 12 gauge. For all-round usage.
  • 16 gauge = .662 inch - Less common lighter variant of the 12 gauge. Would be used by someone wanting a lighter gun, therefore easier to maneuver.
  • 20 gauge = .615 inch - Lighter still than a 16 gauge, preferred as an alternative because of the maneuvering advantage. Used for smaller game: woodcock, widgeon etc.
  • 28 gauge = .550 inch - Noticeably smaller, generally used by children, or for the smallest game.
  • .410 is the smallest gauge in common usage, and doesn't have a gauge name, it is referred to by its bore size. Children's gun, or for pest control, jokingly called 'bumble-bee' guns.