This paper deals with firearms that were employed by the Argentine army in frontier warfare between 1869 and 1877. Documentary information and archaeological assemblages from two contemporary military facilities — Fort General Paz and Fortín Algarrobos — are combined to characterize the armament in service during those years. This was a crucial period, during which a process of modernisation and standardisation of the army’s armament started, centred on the incorporation of Remington single-shot breech-loading rifles and carbines. However, the archaeological record shows that this process was slow and that an astonishing variety of older firearms (flintlocks, percussion smoothbores and rifles) remained in service, causing logistic and operative problems, and reducing the army’s combat effectiveness. The paper then discusses the impact of the incorporation of the Remington guns on frontier warfare, critiquing commonly held determinist characterisations, and placing the Remington’s effect in a broader political and economic context.Fil: Leoni, Juan Bautista. CONICET. University of Buenos Aires. Institute of Archaeology. Buenos Aires; Argentina