The Lee-Enfield rifle was derived from the earlier Lee-Metford, a mechanically similar black powder rifle, which combined James Paris Lee's rear-locking bolt system with a barrel featuring rifling designed by William Ellis Metford. The Lee action cocked the striker on the closing stroke of the bolt, making the initial opening much faster and easier compared to the "cock on opening" of the Mauser design. The rear-mounted lugs place the operating handle much closer to the operator, over the trigger, making it quicker to operate than traditional designs like the Mauser.The rifle was also equipped with a detachable sheet-steel, 10-round, double-column magazine, a very modern development in its day. Originally, the concept of a detachable magazine was opposed in some British Army circles, as some feared that the private soldier might be likely to lose the magazine during field campaigns. Early models of the Lee-Metford and Lee-Enfield even used a short length of chain to secure the magazine to the rifle.

The fast-operating Lee bolt-action and large magazine capacity enabled a well-trained rifleman to perform the "Mad minute" firing 20 to 30 aimed rounds in 60 seconds, making the Lee-Enfield the fastest military bolt-action rifle of the day. The current world record for aimed bolt-action fire was set in 1914 by a musketry instructor in the British Army—Sergeant Instructor Snoxall—who placed 38 rounds into a 12-inch-wide (300 mm) target at 300 yards (270 m) in one minute. Some straight-pull bolt-action rifles were thought faster, but lacked the simplicity, reliability, and generous magazine capacity of the Lee-Enfield. First World War accounts tell of British troops repelling German attackers who subsequently reported that they had encountered machine guns, when in fact it was simply a group of trained riflemen armed with SMLE Mk III rifles.

Standard Mk VII .303 inch cartridge for Lee-Enfield rifle

The Lee-Enfield was adapted to fire the .303 British service cartridge, a rimmed, high-powered rifle round. Experiments with smokeless powder in the existing Lee-Metford cartridge seemed at first to be a simple upgrade, but the greater heat and pressure generated by the new smokeless powder wore away the shallow, rounded, Metford rifling after approximately 6000 rounds. Replacing this with a new square-shaped rifling system designed at the Royal Small Arms Factory (RSAF) Enfield solved the problem, and the Lee-Enfield was born.

[edit] Models/marks of Lee-Enfield Rifle and service periods

Model/Mark In Service
Magazine Lee-Enfield 1895–1926
Charger Loading Lee-Enfield 1906–1926
Short Magazine Lee-Enfield Mk I 1904–1926
Short Magazine Lee-Enfield Mk II 1906–1927
Short Magazine Lee-Enfield Mk III/III* 1907 – present
Short Magazine Lee-Enfield Mk V 1922–1924 (trials only; 20,000 produced)
Rifle No. 1 Mk VI 1930–1933 (trials only; 1,025 produced)
Rifle No. 4 Mk I 1939 – present (officially adopted in 1941)
Rifle No. 4 Mk I* 1942 – present
Rifle No 5 Mk I "Jungle Carbine" 1944 – present
Rifle No. 4 Mk 2 1949 – present
Rifle 7.62mm 2A 1964 – present
Rifle 7.62mm 2A1 1965 – present

By the late 1930s the need for new rifles grew, and the Rifle, No. 4 Mk I was first issued in 1939 but not officially adopted until 1941. The No. 4 action was similar to the Mk VI, but lighter, stronger, and most importantly, easier to mass produce. Unlike the SMLE, the No 4 Lee-Enfield barrel protruded from the end of the forestock. The No. 4 rifle was considerably heavier than the No. 1 Mk. III, largely due to its heavier barrel, and a new bayonet was designed to go with the rifle: a spike bayonet, which was essentially a steel rod with a sharp point, and was nicknamed "pigsticker" by soldiers. Towards the end of the Second World War, a bladed bayonet was developed, originally intended for use with the Sten gun—but sharing the same mount as the No. 4's spike bayonet—and subsequently the No. 7 and No. 9 blade bayonets were issued for use with the No. 4 rifle as well.

During the course of the Second World War, the No. 4 rifle was further simplified for mass-production with the creation of the No. 4 Mk I* in 1942, with the bolt release catch replaced by a simpler notch on the bolt track of the rifle's receiver. It was produced only in North America, by Long Branch Arsenal in Canada and Savage-Stevens Firearms in the USA. The No.4 Mk I rifle was primarily produced in the United Kingdom.

In the years after the Second World War the British produced the No. 4 Mk 2 (Arabic numerals replaced Roman numerals for official designations in 1944) rifle, a refined and improved No. 4 rifle with the trigger hung from the receiver and not from the trigger guard, beech wood stocks (with the original reinforcing strap and center piece of wood in the rear of the forestock on the No.4 Mk I/Mk I* being removed in favour of a tie screw and nut) and brass buttplates (during World War II, the British replaced the brass buttplates on the No.4 rifles with zinc alloy (Zamak) ones to reduce costs and to speed up rifle production). With the introduction of the No. 4 Mk 2 rifle, the British refurbished many of their existing stocks of No. 4 rifles and brought them up to the same standard as the No. 4 Mk 2. No. 4 Mk 1 rifles so upgraded were re-designated No. 4 Mk I/2, whilst No. 4 Mk I* rifles that were brought up to Mk 2 standard were re-designated No. 4 Mk I/3.

The C No.7 Rifle is a .22 single shot manually fed training version of the No.4 Mk I* rifle manufactured at Long Branch.