brass off, v. — Green’s Dictionary of Slang

brass off v.

[? the primary activity of the brass n.¹ (3a); sense 2 suggests the brass casing of a cartridge]

1. (orig. naut.) to tell off, to scold, to grumble.

1925

(con. WWI) Fraser & Gibbons Soldier and Sailor Words 35: Brass Off, To: To grumble.

2. to make money.

1929

Huddersfield Examiner 7 July 9: [advert] It seems only the other day that I ‘brassed off’ with the first investment.

3. to fire at.

1937

W. Prescott-Westcar Big Game, Boers and Boches 151: Instead of getting up close and making sure of their shot, they [...] eventually brassed off at a big bull.