Green’s Dictionary of Slang

1. sexual intercourse [on sex = violence pattern].

1618		Owles almanacke 17: [C]ommon [...] as the blowes of a Spittle whore (hot and dangerous).
1654		Mercurius Fumigosus 14 30 Aug–6 Sept. 120: But first they will give you a bobb, a bobb, / and then they will give you a blow, / And when you have knock’d them once above, / they’l tickle your pockets below.
1788		‘Answer to Darby O’Gallagher’ Songs (publ. Newry) 5: And for every blow / He gave her Below, / He made her two ends for to meet in the middle Sir.
1838		‘My Love Has Got A Weather Eye!’ Rambler’s Flash Songster 28: She does not care for all his blows, / That from his bags he can muster.

2. (US) a pistol.

1928		Hecht & MacArthur Front Page Act III: Say, with that alky rap and the bank job and the big blow on my hip! I should stick around asking questions from a lot of cops!
1929		C.G. Givens ‘Chatter of Guns’ in Sat. Eve. Post 13 Apr.; (list extracted in AS VI:2 1930) 131: blow, n. Pistol.
1935		N. Algren Somebody in Boots 277: Well, where’s your big blow?
1949		Monteleone Criminal Sl. (rev. edn).
1950		Goldin et al. DAUL 30/1: Blow, n. 1. (Rare) A revolver.
1960, 1975		Wentworth & Flexner DAS.