Green’s Dictionary of Slang

(drugs) a package of marijuana cigarettes.

1955		H. Braddy ‘Narcotic Argot Along the Mexican Border’ in AS XXX:2 86: CARTUCHO (Sp.), n. A small package of marijuana cigarettes; from the Spanish word for cartridge or roll of coins.
1957		El Paso Herald (TX) 3 Oct. 17/4: A few examples of [...] ‘calo’ [...] cartucho — a small package of marihuana cigarets.
2001		ONDCP Street Terms 5: Cartucho (Spanish) — Package of marijuana cigarettes.