the US. Some 9×19mm submachine guns, including the m/942, the Portuguese m/948, and the West-German manufactured version of the Israeli Uzi (known in Portuguese service as the Pistola-Metralhadora m/61) were also used, mainly by officers, NCOs, horse-mounted cavalry, reserve and paramilitary units, and security forces. Within a short time, the Portuguese Army saw the need for a modern selective-fire combat rifle, and in 1961 adopted the 7.62×51mm NATO caliber Espingarda m/961 (Heckler & Koch G3) as the standard infantry weapon for most of its forces, that was produced in large quantities in the Fábrica do Braço de Prata, a Portuguese small arms producer. However, quantities of the 7.62×51mm FN and Belgian G1 FAL battle rifle, known as the m/962, were also issued; the FAL was a favored weapon of members serving in elite commando units such as the Caçadores Especiais. At the beginning of the war, the elite airborne units (Caçadores Pára-quedistas) rarely used the m/961, having adopted the modern 7.62 mm NATO ArmaLite AR-10 (produced by the Netherlands-based arms manufacturer Artillerie Inrichtingen) in 1960.Afonso, Aniceto and Gomes, Carlos de Matos, Guerra Colonial (2000), , pp. 183–184 In the days before attached grenade launchers became standard, Portuguese paratroopers frequently resorted to the use of ENERGA anti-tank rifle grenades fired from their AR-10 rifles. Some Portuguese-model AR-10s were fitted with A.I.-modified upper receivers in order to mount 3× or 3.6× telescopic sights. These rifles were used by marksmen accompanying small patrols to eliminate individual enemy at extended ranges in open country. After the Netherlands embargoed further sales of the AR-10, the paratroop battalions were issued a collapsible-stock version of the regular m/961 (G3) rifle, also in 7.62×51mm NATO caliber. The powerful recoil and heavy weight of the 7.62mm NATO cartridge used in Portuguese rifle-caliber arms such as the m/961 limited the amount of ammunition that could be carried as well as accuracy in automatic fire, generally precluding the use of the latter except in emergencies. Instead, most infantryman used their rifles to fire individual shots. While the heavy m/961 and its relatively lengthy barrel were well-suited to patrol operations in open savannah, it tended to put Portuguese infantry at a disadvantage when clearing the low-ceilinged interiors of native buildings or huts, or when moving through thick bush, where ambush by a concealed insurgent with an automatic weapon was always a possibility. In these situations the submachine gun, hand grenade or rifle-launched