Green’s Dictionary of Slang

1. (US milit.) used of various ‘assistants’, e.g. an officer’s servant.

1906		C. M’Govern ‘Soldier Sl.’ in Sarjint Larry an’ Frinds.
1906		C. Fowler letter 18 Feb. in Tomlinson Rocky Mountain Sailor (1998) 22: On some ships, a man is detailed to assist the mess cook in his mess at meal times. Men so detailed are call[ed] ‘strikers’.
1907		C. Fowler letter 16 Jan. in Tomlinson Rocky Mountain Sailor (1998) 201: The Engineer's Writer [...] has a ‘striker’ in his office .
1914		E. Genet letter 6 May in Channing War Letters of Edmond Genet 12: I was detailed last Saturday. The position is that of striker for yeoman.
1928		(con. WW1) B.J. Doty Legion of the Damned 204: [H]e was ordonnance to an officer—what in our army is a ‘striker’ or, more popularly, a ‘dog-robber’.

2. (US Und.) a recruit for a motorcycle gang.

1986

C. Stroud Close Pursuit (1988) 271: Mokie had talked about his friend who was a striker – a recruit – for a motorcycle gang in the Bronx.