A conventional large-caliber artillery piece by all accounts, the 155mm L33 modello Argentino towed field gun was in development during the 1970s, intended to replace the aged and outgoing M114 155mm systems of American origin. The original M114 was introduced in 1942 during World War 2 with the US Army and went on to see production reach over 10,300 examples. However, time and technology soon forced the Argentine government to pursue a modern venture and this resulted in the indigenous L33 system by CITEFA - the government-run "Instituto de Investigaciones Cientificas y Tecnicas de las Fuerzas Armadas" (translating to "Institute of Scientific and Technological Research of the Armed Forces"). Production was handled locally by DGFM.
While utilizing tried-and-true principles of proven artillery systems elsewhere, the field gun was essentially a developmental offshoot of the 155mm gun barrel utilized in the French Mk F3 self-propelled artillery vehicle produced by Nexter and appearing in 1962. As such, it could fire the same ammunition and utilize the same replacement parts which, considering the Argentine military already utilized a stock of Mk F3 vehicles, made logistical sense. The original L33 field gun was adopted in 1977 and this was followed by an improved version in 1981 - therefore, each became technically recognized as the "Modelo 77" and "Modelo 81" respectively.
Design-wise, the L33 was developed through a rather traditional arrangement, largely in accordance with other existing field systems showcased elsewhere globally. The barrel was capped by a double-baffled muzzle brake and set within a large recoil reduction system. The entire unit was then fitted to a heavy duty mounting assembly which provided the necessary elevation and traverse controls (manually-activated hand wheels). Elevation was limited to -10 and +67 degrees with traverse reaching 70-degrees to either side. The mounting system was set atop a two-wheeled rubber-tired carriage in a "split trail" configuration. The arms were lowered to absorb recoil and then doubled as the tow arms when connecting to the rear of a mover vehicle. A circular plate was lowered under the carriage when the weapon was made ready to fire and this raised the rubber tires from the ground. The L33 was loaded from the rear through am interrupted screw-type breech in the traditional sense and the entire function of the gun requiring a crew of 6. Overall weight of the weapon was 18,000lbs and the barrel measured in at nearly 17 feet long (16.10") with a 6.1 inch diameter. The L33 primarily utilized a large, high-explosive 155mm projectile and could reach out to 20 kilometers. A special assisted projectile was developed to engage target areas as far out as 24 kilometers. Muzzle velocity was listed at 2,510 feet per second. Illumination, smoke and shrapnel rounds eventually figured into the munitions mix.
The Argentina Army received a total of 109 L33 gun systems while the only other operator became Croatia which took delivery of 8 guns.
On April 2nd, 1982, Argentine military forces (directed by its military-run government) invaded the neighboring Falkland Islands group which lay under British control. This sparked the Falklands War of 1982 which presented the British with a logistical nightmare when moving men, machine and supplies from the United Kingdom southwards across the Atlantic towards the Falklands island group. Several Modelo 77 series guns were employed by the Argentines in defense of key positions around Stanley where they were limited by their cumbersome size which prohibited rapid mobilization on a fluid front. The guns were strategically stationed along various ridges to help counter the off-shore barrage of naval gunfire being encountered from Royal Navy warships. Modelo 77 guns were brought to the island via airlift via Lockheed C-130 Hercules transports of the Argentine Air Force. After roughly three-and-a-half months of intense fighting, the British eventually wrestled control of the island from the Argentines while taking some 11,300 prisoners. The Argentine Army suffered 649 total casualties in the fighting to the British 258 (115 prisoners were taken by the Argentines as well). The Falklands War ended on June 14th, 1982 and led to the collapse of the Argentine military government in 1983 while the British military proved its logistical prowess by its massive naval undertaking and showcased to the world the unique qualities of its new VTOL (Vertical Take-Off and Landing aircraft - the Harrier/Sea Harrier jump jet).
British troops managed to capture four complete Modelo 77 guns before the end of the fighting. The L33 was to be heaviest artillery piece utilized by the Argentine Army during the conflict. Despite its age, the weapon remains an active portion of the modern Argentine Army today (2012).