膛線 [－线]

Jyutping tong4 sin3
Pinyin táng xiàn

Definitions (CC-CEDICT)
  1. rifling (helical grooves inside the barrel of a gun)
Definitions (Wiktionary)
  1. noun
    rifling
Definitions (Kaifangcidian)
  1. （沒有對應漢語詞彙）