part which I call the “safety”—the part which actually locks the striker—is called the “locking bolt,” and the part I call the “bolt lock,” which actually locks the bolt, is called the “safety catch.”)
Left-side view of the No. 1 Mark III Lee-Enfield action.
Top view of the No. 1 Mark III action showing cutoff pulled out; the bolt will pick up cartridges from the magazine as the bolt is operated.
The sear, an L-shaped piece of metal, is held in place by, and pivots on, a screw under the receiver. This screw also holds the bolt-head release spring. It is under tension from a flat V-spring positioned between the sear and magazine catch which also supplies tension to these parts. The trigger pivots on a pin in the trigger guard. The curved trigger is grooved; its top part, which contacts the sear, has two bumps which provide the common double-stage military pull.
The detachable staggered-column box magazine, of ten-round capacity, is made from heavy-gauge sheet metal. The follower has a raised rib on its left side which causes the cartridges to lie staggered in the magazine. The follower is tensioned by a W-shaped spring. Curved lips at the front and rear of the magazine opening hold the cartridges in the magazine.
The magazine box, positioned in the milled-out bottom of the receiver by the trigger guard/magazine plate, is held up by the magazine latch. Partial cartridge guide lips, milled into both sides of the magazine well, hold and guide the cartridges into the chamber as they are fed out of the magazine by the bolt. The magazine can be single loaded whether in or out of the rifle, or it can be loaded with a stripper clip while in the rifle.
The No. 1 SMLE action has a cartridge cutoff, a flat triangular piece of metal positioned in a slot milled in the right receiver wall. It pivots on a screw through the bottom front edge of the receiver. Pushed in (engaged), the cutoff slides over the cartridges in the magazine, so the bolt can be closed without picking up a cartridge. This allows single-round loading, holding the cartridges in the magazine in reserve. Pulled out, the cutoff is inoperative, letting the bolt pick up the topmost cartridge in the magazine as it is closed.
The ejector is merely a small stud screw threaded into the left receiver wall. When the bolt is opened, the extracted case or cartridge slides along the inside wall of the receiver until its head strikes the end of the ejector screw—the bolt nearly all the way open. This tips the case to the right, out of the action.
A gas-escape hole in the bolt head vents any powder gases which might enter the firing-pin hole in the case of a pierced primer. It vents the gases upward along the edge of the left receiver wall. There is another small oblong gas-escape hole in the left side of the receiver ring, in line with the space occupied by the cartridge rim between the face of the bolt and barrel. There is also a notch cut into the rear of the receiver ring, just ahead of the extractor lug on the bolt head; this space, and the oblong hole opposite it, should expel any gases escaping from a ruptured case head.
A new system of model designation was introduced in May, 1926. The SMLE Mark III became the No. 1 Rifle, Mark III. The Pattern 1914 Rifle (known in the U.S. as the 1917 Enfield) became the No. 3 Rifle. The No. 4 Rifle, Mark I, was a development of the SMLE Mark VI.
The No. 1 Lee-Enfield (also known as the SMLE, for Short Magazine Lee-Enfield), introduced shortly after 1900, underwent many changes before the No. 4 Lee-Enfields were introduced about 1939. We are not concerned here with the many minor changes in the action, since it remained structurally the same. Officially, as each change was adopted, the model designation was changed, beginning with Mark I and continuing to Mark VI and including such asterisk or “starred” (*) designations as the Mark I*, etc., etc. The No. 1 action itself remained substantially the same for over 30 years, and since it was made in large quantities, it is the most common one.
The No. 4 Lee-Enfield Action
Little development was done on the Lee-Enfield rifle after WWI since the rifle and action had proved reliable during that conflict. Nor was there much need to make many additional rifles—at least not until WWII loomed into sight. However, it had been previously found that the rifle could be simplified and improved, and the action made somewhat stronger. The development work done accordingly was toward making the rifle more accurate, simpler and stronger. For example, it was found that the rifle gave better accuracy with an aperture sight mounted on the receiver and that there was no real need for the magazine cutoff. Thus, in the late 1930s, when the British again needed rifles, they adopted the Mark VI, a simplified and improved version that became the No. 4 Lee-Enfield.
Here are some of the changes adopted:
1) The cutoff was eliminated, the machining for it omitted. This left the right receiver wall stronger than before, simplified and stiffened the action, and left more metal in the right wall to support the right locking lug.
2) The bridge was made a bit higher so that a leaf aperture sight could be mounted.
3) The front of the bridge was also made a bit higher, so that a connecting strip of metal joining these projections formed a much smaller and neater clip-charger guide bridge.
Top view of the No. 1 Mark III Lee-Enfield action. Magazine cutoff is shown depressed.
No. 1 Mark III Lee-Enfield action, open, shown with stock bolt.
4) The thumb notch in the left receiver wall was made shallower, further strengthening the receiver.
5) The bolt head was altered, as well as the method by which it was guided and retained. The extractor lug was made smaller, and instead of engaging over the edge of the right receiver wall, it moved in a groove cut inside the wall. On early No. 4 actions, a plunger-type bolt head release, fitting in a mortise cut into the receiver, could be depressed to release the bolt head. Later, this release was omitted; instead, a notch cut out of the bolt head groove in the front of the right receiver wall allowed the bolt head to be rotated at this point for removal of the bolt from the action. With this change, the rifle became the No. 4 Mark 1*.
6) The safety shape was changed and a new safety spring used, eliminating the safety washer.
7) The left side of the bolt head was made flat to allow a greater amount of powder gases to escape out of the bolt head hole and past the receiver wall. The gas-escape hole in the left of the receiver was enlarged and made round.
In addition to the above, a groove was milled in the right locking lug/guide rib to make the bolt lighter. There are a number of changes in the configuration of the receiver which were the result of eliminating or simplifying the machining operations:
On late No. 4s, the trigger was pivoted in the receiver instead of in the trigger guard. The No. 4 actions in which the trigger was pivoted in a bracket brazed on to the butt socket became the Mark ½. Later, when the brazed-on bracket was eliminated and the trigger pivoted directly to the butt socket, the designation was changed to Mark 1/3.
The No. 5 Lee-Enfield Jungle Carbine has the same action as the No. 4.
Takedown and Assembly
Make certain the rifle is unloaded. Remove the magazine by lifting up the magazine latch
