The original John Browning M1918 BAR (Browning Automatic Rifle) was introduced during World War 1 with American forces and saw more widespread during World War 2 while serving into the 1960s(it can still be found in certain places today). Colt eventually produced a version of the BAR for the commercial market and foreign adoption of the weapon ensued. The Belgian concern of Fabrique Nationale took on license production of the automatic rifle in 1930 as the "FN Mle 1930", this based on the "Colt Automatic Machine Rifle Model 1925" offering of 1925.
Prior to World War 2, Fabrique Nationale took to modernizing the Mle 1930 in 1932 to become the "FN Mle D" (or "Type D") for their still remained need for BAR-type weapons especially in the light machine gun role. FN took to modifying their BARs in two distinct ways - institution of a "quick-change" barrel feature and simplifying the design of the receiver. In these two initiatives, the Mle Type D now sported the ability for the operator to change out an overheating barrel with a cool unit and not risk the detrimental effects of an overheated barrel (deformation, fracturing of the assembly). This allowed the weapon to undertake the more defined suppression fire role where voluminous fire was a key quality. The simplification of the receiver and its internal working components meant that the weapon was lighter than in previous BAR iterations and proved less expensive to produce in number. Additionally, cleaning, maintenance and repair were all bettered through the initiative. The weapon was produced in three chamber sizes - the original utilizing the 7.92x57mm Belgian Mauser cartridge and, in the post-war years, the .30-06 Springfield 7.62x51mm NATO cartridges. In the latter (designated as the "FN Mle DA1"), the weapon fed from FN FAL-type straight box magazines. Belgian BARs were noticeably different from their American cousins by their use of cooling "fins" along the barrel - though these were of debatable value. Other key Belgian-inspired features were retained from the Mle 1930 - the carrying handle, heavy-duty barrel and folding bipod.
The end-product resulted in a fine weapon system that was an improvement over the original BAR iteration. However, the new weapon was still limited by its 20-round detachable box magazine which was not addressed in the redesign and thusly limited the tactical value of the Mle D as a light machine gun. It was still too heavy and clumsy to wield as a battle rifle or assault weapon and, adding insult to injury, time had passed the BAR design by to the point that there proved better offerings for the light machine gun role on the world stage. World War 2 disrupted much meaningful armaments production in Belgium and the Mle D did not go one to see widespread use - being limited to the armies of Belgium and Egypt and little more. The Mle D survived longer in Egyptian service than in Belgian service before being replaced by Soviet offerings.