I did some research and this is what I came up with as far as the background on Argentine 1911's:
In 1914, the Argentine military adopted the Colt M1911 as their standard military sidearm and contracted with Colt to supply these guns. Argentina took shipment of 2,151 of these weapons between 1914 and 1919. Among them were the following: 321 pistols received in 1914 marked MARINA ARGENTINA (Argentina Navy), S/N C6201-C6400 and C11501-C11621; 1000 received in 1916, S/N C20001-C21000; 400 received in 1919 within the S/N range of C86790-C116594. These pistols went through two different channels. The battleships that were being made in the USA for Argentina received the Navy pistols directly. Pistols delivered to Argentina went through the London Armoury Company. The 1,000 pistols received in 1915 were marked with Argentine crests and property numbers 1 to 1,000 on the tops of the slides. These pistols were designated "Pistola Colt Modelo Argentino 1916.
In 1923, Argentina adopted an armaments bill that would eliminate Argentine dependency on foreign arms. Under this bill, the Argentine Congress authorized appropriations for a military modernization program and prepared the infrastructure for a domestic arms industry. In accordance with the new law, an aircraft factory was established in 1927, a munitions factory in 1933, a small steel mill in 1934, and a small arms factory in 1936, all of which were managed by Argentine army officers.
In 1927, the Argentine Commission for Foreign Acquisitions negotiated a contract with Colt for the manufacture of M1911A1 .45 caliber self-loading pistols specially marked and serial numbered in a separate series, and secured a licensing agreement giving the Argentine government the right to manufacture these pistols.
The agreement specified: 1) that Colt would manufacture 10,000 Colt automatic pistols, caliber .45, Ejercito Argentino Modelo 1927, for the Argentine Army; 2) that the complete knowledge base for future production of the pistols in Argentina, including drawings, manufacturing instructions, material specifications, tool requirements, etc., would be transferred to Argentine control; and 3) that Argentine technicians would be trained in manufacturing operations and inspection.
THE 1927 HARTFORD ARGENTINE ARMY MODELS
The 10,000 Hartford Colts made for Agentina prior to production of Sistemas were delivered from 1927 to 1933, serial #’s 1-10,000." The production period was from July 28, 1927 to February 16, 1928. Serial numbers were stamped in Colt’s italic numbers on top of the slides, under the mainspring housing, and (usually) on top of the barrel.
On the left side of the slide (the Colt logo is stamped behind these lines):
"COLT'S PT. F.A. MFG. CO. HARTFORD CT. USA"
"PATD APR. 20, 1897,SEPT. 9, 1902,DEC. 19, 1905,FEB. 14, 1911,AUG. 19, 1913."
On the right side of the slide is the Argentine Crest and:
"EJERCITO ARGENTINO"
"COLT CAL. 45 MOD. 1927"
Ejercito Argentino is the Argentine Army, but some of the Hartford's were issued to Policia Maritima, Argentinas Shore Patrol. For production of Colt 1911A1's in Argentina, Colt engineers supervised the set-up of the production equipment, which was acquired from the Fritz Werner company in Germany, a maker of arms-manufacturing machinery still in business today.
From 1927 to 1942, 14,000 Sistema pistols (from Sistema Colt, indicating made on the Colt system (machinery) were produced at the Esteban de Luca Arsenal in Buenos Aires, S/N 10,001-24,000, the serial numbers continuing from the Hartford run.
In 1941, after a decade of planning, Argentines established a large and diversified military-industrial complex under the overall supervision of the Direccion General de Fabricaciones Militares (D.G.F.M.), the Military Manufacturing Agency. Similar to the US Ordnance Department, the agency was run by the military and military officers managed the manufacturing plants. Among other products, this agency would eventually, through contractual agreements, oversee the production of identical copies of Colt M1911-A1, Brownings Hi Power, and FN FAL rifle.
In 1945, after construction of the state-owned Fabrica Militar de Armas Portatiles (F.M.A.P.), Small Arms Factory in Rosario, Santa Fe (250 miles from Buenos Aires), assembly of Sistemas was transferred to the new plant and another 88,494 pistols were produced through 1966. This factory was named for Domingo Matheu, a 19th century military official who was active in the early development of the nation's arms industry.
Sistema Colts were manufactured in accordance with Colt's 1927 drawings. They were identical to US military M1911-A1 pistols except for 6 minor cosmetic differences, and parts were interchangeable.
The differences were: a) the markings, b) the grips, c) a black oxide bluing, d) a sharp edge on the rear of the hammer, e) a sharp edge on the heel of the grip safety, f) indented checkering on the mainspring housing.
Reposted from a thread on the 1911 forum. My thanks to member "butchblocs" for posting this over there.