[5] It was developed per jungle fighting experiences in the Pacific War that led the British to decide "a rifle shorter and lighter" than the regular Lee–Enfield was critical for better mobility.

Experience of jungle fighting in 1943 identified that mobility was critical and to that end the weight of equipment carried by the individual soldier needed to be reduced.

5 buttpad significantly reduced the contact area with the user's shoulder, increasing the amount of felt recoil of the firearm.

5 carbine's 4.06 ft⋅lbf (5.50 J) extra recoil energy, 1.44 ft⋅lbf (1.95 J) was caused by adding the conical flash suppressor (muzzle shroud).

It was used in the Far East and other jungle-type environments (hence the "jungle carbine" nickname) and was popular with troops because of its light weight (compared to the SMLE and Lee–Enfield No.

4 Mk I rifles then in service) and general ease of use,[12] although there were some concerns from troops about the increased recoil due to the lighter weight.

Tests conducted during the mid to late 1940s appeared to confirm that the rifle did have some accuracy issues, likely relating to the lightening cuts made in the receiver, combined with the presence of a flash suppressor on the end of the barrel.

[16] The British government officially declared the jungle carbine possessed faults "inherent in the design" and discontinued production at the end of 1947.

[17] However, modern collectors and shooters have pointed out that no jungle carbine collector/shooter on any of the prominent internet military firearm collecting forums has reported a confirmed "wandering zero" on their No.

[19] The rifle was first issued to British airborne forces in Norway towards the end of the Second World War; these were troops that were likely to be sent to the Far East for an invasion of Japan.

[5] Though they did not invent the name, the designation "jungle carbine" was used by the Golden State Arms Corporation in the 1950s and 1960s to market sporterised military surplus Lee–Enfield rifles under the "Santa Fe" brand.

[5] The easiest way to identify a "jungle carbine" rifle is to look for the markings on the left hand side of the receiver; a genuine No.