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Lee-Enfield No. 1 Mk III (SMLE)

• moderate
• Shop tier 2
• medium confidence
• Rifle
• surplus
• milsurp
• corrosive ammo
• historic
• rear locking
• detachable magazine
• service rifle

field strip ~3 min · reassembly ~4 min · detail strip ~35 min

Specifications

Model-specific safety

• These rifles are decades old and most have been arsenal rebuilt with mixed parts. Have headspace checked by a gunsmith before firing any rifle of unknown history.
• Surplus ammunition of this era is frequently corrosively primed. Clean with a water-based solvent the same day you shoot.
• Newly imported rifles are often packed in cosmoline throughout, including the bolt and firing pin channel. Clean it out before firing — a firing pin held forward by congealed grease causes slam fires.
• Headspace on a Lee-Enfield is set by the bolt head, which comes in numbered sizes. Surplus rifles are frequently rebuilt with mixed parts and a rifle with the wrong bolt head can have dangerous headspace. Gauge any rifle of unknown history.
• The No. 1 SMLE uses a different bolt release from the later No. 4 — the two are not the same procedure. Do not apply No. 4 instructions to a No. 1.
• This is a rear-locking action, which flexes more than a front-locking design by design. That makes headspace checking more important rather than less.
• Although the magazine is detachable, it was intended to stay with the rifle and be charger-loaded. Verify the chamber independently of the magazine.

Under spring tension

• Mainspring inside the bolt
• Magazine follower spring

Easily lost parts

Bolt components · Firing pin · Extractor · Floorplate components

Tools

Shop difficulty

Shop tier 2 Tier 2 — moderate among rifles and carbines, for the full job: strip to the parts that get coated and put it back together working. Same bolt and striker-tool traps as the No. 4, plus more woodwork: a nose cap with two screws, separate front and rear handguards (the rear one has thin flanges around the rear sight), outer band, and a stock bolt. It has more parts than the No. 4, but they all go in order, with no timing.

Parts: 70 numbered parts (complete No. 1 Mk III (SMLE) rifle incl. magazine per the Gun Digest exploded drawing legend 'No. 1, Mark III (SMLE) Bolt-Action Rifle', keys 1-70. The rear sight is one key ('Rear Sight Assembly with), from The Gun Digest Book of Exploded Gun Drawings (975 isometric views) - 'No. 1, Mark III (SMLE) Bolt-Action Rifle' — Gun Digest Books / Krause Publications (scan on archive.org), p. book p. 534 (PDF page 535) archive.org [5].

Bench time: about 40 min to strip, 55 min to rebuild (estimate). Estimate: as the No. 4 plus the nose cap, outer band, front and rear handguards and cut-off. Rebuild longer for the striker, the handguard clips and the nose cap screws.

Small parts: 3 pins, 8 springs, 0 detents or plungers (counted by name in the same legend. Pins: 20 magazine catch pin, 24 trigger pin, 42 front sight pin (1 firing pin not counted). Springs: 5 extractor spring, 6 firing pin spring, 11 safety spring, 19 b)

What comes off for coating

• Bolt: bolt head, striker screw, striker, mainspring, cocking piece (with tool), extractor and spring — striker tool (notched tube)
• Receiver: safety catch and spring, magazine cut-off, magazine catch, trigger (with trigger guard), rear sight — drift punch
• Stock and furniture: front and back nose cap screws, nose cap, outer band and swivel screw, front handguard, rear handguard, front/back trigger guard screws, trigger guard, fore-end, buttstock (leather wad and stock bolt), butt plate — long screwdriver plus wrench for the stock bolt

Special tools

• Striker tool (3/8 in tube with two notches) — Unscrewing the striker
• Fine drift punch — Extractor spring
• Long wide-bladed screwdriver plus wrench — Stock bolt

Known pain points

• The striker is unscrewed from the cocking piece with a notched tube tool while holding inward pressure, or the mainspring ejects it. (both)
  Source: Exploded View: Short, Magazine Lee-Enfield, Mk III — American Rifleman (NRA) americanrifleman.org [3] — “engage the striker (57) and unscrew it from the cocking piece (54) making sure to maintain an inward pressure against the mainspring to keep it from forcibly ejecting the striker when it is totally unscrewed.”
• The rear handguard clips to the barrel and has thin flanges around the rear sight that crack if levered. (both)
  Source: Exploded View: Short, Magazine Lee-Enfield, Mk III — American Rifleman (NRA) americanrifleman.org [3] — “Unclip the rear handguard (66) from the barrel, taking care not to damage the thin flanges that surround the rear of the backsight assembly (5) (Fig. 5).”
• The buttstock bolt is reached through the butt trap after pulling a leather wad, and usually needs a wrench on the screwdriver. (both)
  Source: Exploded View: Short, Magazine Lee-Enfield, Mk III — American Rifleman (NRA) americanrifleman.org [3] — “using a wrench for extra leverage, unscrew and remove the stock bolt.”
• The striker has to be unscrewed from the cocking piece with a notched takedown tool while holding the mainspring; the pamphlet warns a makeshift rig can damage it. (both)
  Source: Lee-Enfield Rifle Manual, No.1 Mk III, No.3, No.4, No.5 (Pamphlet 1) — unknown publisher (archive.org "Lots of gun PDFs") archive.org [4] — “may cause damage and should be left to a qualified gunsmith.”
• The V-shaped extractor spring is eased out through a tiny hole in the bolt head with a fine punch and jumps if not covered; it seats on a small projection going back. (both)
  Source: Lee-Enfield Rifle Manual, No.1 Mk III, No.3, No.4, No.5 (Pamphlet 1) — unknown publisher (archive.org "Lots of gun PDFs") archive.org [4] — “To reassemble, place the spring into the extractor slot and seat the small projection on the spring into its seat in the bolt head.”

Fit or check on rebuild

• Bolt and bolt head fitted to the rifle — Bolts and bolt heads are fitted to their own boltway (headspace); keep the serial-matched bolt with the rifle
  Source: Lee-Enfield Rifle Manual, No.1 Mk III, No.3, No.4, No.5 (Pamphlet 1) — unknown publisher (archive.org "Lots of gun PDFs") archive.org [4] — “They have been fitted to their respective boltways.”
• Fore-end/king screw and band tension — Fore-end bedding pressure and band screw tension affect zero; re-zero after the woodwork is off

This is Pew-Takedown's rating, not the manufacturer's. How tiers are rated. Forum reports are owners' experience, not specifications.

Procedures

Torque specifications

No sourced torque values from the manufacturer are recorded for this firearm. Where a fastener has a specified torque — action screws, scope bases, muzzle devices, barrel nuts — get it from the manufacturer or a gunsmith rather than estimating it.

Function check

• Verify the rifle is unloaded — chamber and magazine — before each check.
• Cycle the bolt and confirm it cocks and closes fully into battery.
• With the action cocked, engage the safety and press the trigger. The striker must not release.
• Disengage the safety without touching the trigger. The striker must not release.
• Press the trigger and confirm the striker releases with a firm snap.
• Load dummy rounds and confirm they feed and eject cleanly.
• If you have any doubt about the rifle’s history, have headspace gauged by a gunsmith before firing live ammunition.
• Confirm the two-stage trigger has a distinct first stage and a clean second stage.
• Confirm the magazine cut-off works if your rifle has one — many Mk III rifles do, Mk III* rifles generally do not.

Maintenance

Lubrication points

• Bolt lugs and raceways
• Cocking cam surfaces
• Extractor
• Trigger and sear contact

Cleaning notes

Surplus ammunition of this era is frequently corrosively primed. After shooting it, flush the bore, bolt face, and gas system with hot soapy water or a water-based solvent the same day, dry completely, then oil. Keep the firing pin channel clean and dry — a pin held forward by congealed cosmoline causes slam fires.

Suggested inspection interval: roughly every 300 rounds. This is a general guideline, not a manufacturer specification.

Wear parts to inspect

Firing pin and its protrusion · Extractor · Bolt lugs · Crown (inspect for cleaning rod wear) · Magazine follower and spring

Common issues

Also covers

The procedures above are reported to apply to: Rifle No. 1 Mk III and Mk III* · Lithgow and Ishapore SMLE production. Verify against the manual for your specific model.

Similar manual of arms

• Lee-Enfield No. 4 Mk I

Sourcing