Green’s Dictionary of Slang

1. (Aus.) a vocal, loquacious individual.

1914

Sport (Adelaide) 12 June 4/6: F.B., the Blocks blowpipe, says he would like to go to China to teach the heathens.

2. (US) a rifle.

1921		DN V 111: Blow-pipe, n. A rifle.
1944		R.F. Adams Western Words (1968).
1954		Indep. Record (Helena, MT) 9 Oct. 3/7: When you talk about a ‘blowpipe,’ you really mean a rifle.
1960, 1975		Wentworth & Flexner DAS.