Like most countries that manufacture guns, Argentina has also done its share of research trying to come out with a decent (light, compact, accurate, controllable) full-auto pistol. The whole thing started at the Government-owned Fábrica Militar de Armas Portátiles “Domingo Matheu”, in Rosario, Santa Fe Province, in 1974 as an in-house effort. Being an established licensed manufacturer of the FN Browning Hi-Power, the factory found it proper to use it as the basis for what was called the SPA (Sub Pistola Ametralladora, Sub Machine Pistol).
Since the Hi-Power’s usual 9x19mm cartridge was recognized as too-much powerful for a hand-held, full-auto, very-high-rate-of-fire gun, the guys down South decided to use a somewhat milder cartridge, but still capable of producing serious wounds on humans. They chose the 7.63x21mm Mannlicher cartridge for long (1905-1916) used in the Argentine Army Austrian-made Steyr-Mannlicher Model 1905 delayed-blowback semi-auto pistols. With an 85-grain bullet coming out of the gun’s 160mm barrel at 312 m/s, the ammo had been locally-produced in vast numbers for years and the tooling had been retained for eventual manufacture re-entering.
The resulting SPA involved only twelve new or modified parts, the most evident being the 159mm long barrel which protruded about 40mm from the slide, with 16-, 25-, and 40-round magazines being made for the single prototype built. The cyclic rate of fire was in the region of 1,000 rounds per minute. The fire selector was a button located immediately above the trigger: pushed from right to left, the pistol fired full auto; from left to right, semi auto.
The Army high-brass, however, later provided funding for five prototypes chambered for 9x19mm, but the resulting guns were untamed beasts. I had a chance to briefly fire one of these in a visit to “Domingo Matheu” in February 1990, and can summarize the SPA performance as “BRRRR… an empty magazine… and three or four hits on a man-sized silhouette at three or so meters away!” That’s probably why the SPA project was shelved a short time after it started.