The Lee-Enfield bolt-action rifle to emerge from Britain in 1895 became one of the classic service rifles of its time - joining the likes of the Russian Mosin-Nagant, the American Springfield M1903 and the German Mauser. The original versions were known as "MLE" for "Magazine Lee-Enfield" and these were followed in 1907 by the "SMLE" signifying "Short Magazine, Lee-Enfield" which gave excellent service during World War 1 (1914-1918).
The line survived in frontline service for decades and was still in use by the time of World War 2 (1939-1945). By 1943, it became apparent to British authorities that its forces, and those of the Commonwealth, operating in the jungles of the Pacific and Southeast Asia required a more compact gun for the confines associated with jungle warfare. A full-length rifle form. and the inherent effective ranges it offered, did little in areas where trees and mountains consistently broke up the landscape - meaning more short-to-medium-range fighting was to be expected. This led to a new model being introduced in 1944 derived from the Lee-Enfield line - the "Rifle, No.5 Mk I" which came to be informally known as the "Jungle Carbine".
As a carbine, the No.5 was nothing more than a purposely shortened form of an original long gun, in this case the Lee-Enfield No.4 SMLE. The No.5 was a replica of the No.4 in every way (including its .303 British chambering) save for the shortened barrel assembly which, in turn, forced a reduced-length forend to be used. As this shortening procedure took away from the effective range of the original rifle design, the sights were appropriately modified for the new carbine role (out to 800 yards). Two other modifications followed - one being a conical muzzle attachment at the business end of the barrel to serve as a "flash hider" and the other being a pad added to the shoulder stock. The reduced length firearm still retained the ferocious recoil of the .303 round so the pad was intended to absorb some of this force before imparting the remainder against the operator. The flash hider was also instituted in an effort to help conceal the firer's position - normally this flash was somewhat contained by a longer barrel but this was not the case with the revised Jungle Carbine.
In practice, the carbine was not an outright success for its operators did not appreciate the still-heavy recoil effects of their smaller, lighter guns - though conversely they appreciated the more compact and lightweight form that was offered to them on long marches through the jungle. Additionally there emerged an issue with sighting of the weapon in which the gun - for whatever reason - could not retain its "zeroed in" setting through subsequent shooting, making for one inaccurate and inconsistent rifle system in the end. This ensured that the Jungle Carbine would not see a lengthy service life as a frontline solution for at one point it was envisioned as the next standard issue service rifle for British Army personnel, succeeding the No.4 line.
First users of the No.5 Jungle Carbine included the 1st Airborne Division of the British Army and these saw combat service in Europe during 1945. Production continued on after the war until 1947 and from this point forward the carbine saw extended use in the hands of special forces elements. Some were still in play during Malayan Emergency (1948-1960) and the Korean War (1950-1953) that followed World War 2 action.
The No.5 Jungle Carbine featured an overall weight of 7.15 pounds, a reduction from the No.4's 8.8 pound carry weight, and overall length was a handier 39.5 inches, down from 44 inches seen in the original Lee-Enfield design. Muzzle velocity remained roughly equivalent at around 2,400 to 2,500 feet-per-second range and feeding was from the same 10-round magazine holding .303 British cartridges (2 x 5-round charger clips). Manufacture of the gun was through the Royal Small Arms Factory (RSAF) of Enfield Lock in Middlesex.