Green’s Dictionary of Slang

1. (US) a large pistol.

1881

Sat. Rev. (London) 9 July 40/2: A Californian bull-doser is a pistol which carries a bullet heavy enough to destroy human life with certainty.

2. (US, also bulldoze) a bully, a thug.

1878		North Amer. Rev. CXXVII 426: The great ‘bulldozer’ of Europe [F&H].
1880		Omaha Dly Bee (NE) 28 Aug. 4/2: [headline] Bulldozers and Spotters Intimidate Respectable Voters.
1892		Courier-Journal (Louisville, KY) 1 Oct. 6/3: The people of Louisville [...] will never surrender their rights to Johnny Davenport’s proposed gang of ballot-box stuffers and bull-dozers [DA].
1912		Van Loan ‘Behind the Mask’ in Ten-Thousand-Dollar Arm 227: A bulldozer, a bluffer, a loud talker, a button snatcher.
1929		M. Levin Reporter 261: [of a robber] And now let us return to Barney (Bulldoze) Rogers.
1930		D. Ahearn Confessions of a Gunman 223: He was always known as a bulldozer [...] People feared him.
1968		in B. Jackson In the Life (1972) 181: He’s a bulldozer [...] He wants to thow his weight around.