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Meaning of Thirty-thirty.

30-30

Pronunciation: (thûr'tē-thûr'tē), [key]
— n.
  1. a rifle using a cartridge approximately .30 inch in diameter, originally having a powder charge of 30 grains but now of various charges.
  2. the cartridge itself.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.