Disassembly: Lahti m/40

The Lahti m/40 pistol is a cinch to strip but a bit of a hassle to fully disassemble.  Due to some rivets and roll pins we couldn’t quite go all the way with the one we had on loan but what we did get away with should be more than enough.




Before we begin C&Rsenal would like to thank East Coast Guns of Summerville, SC, for donating this piece for the article.  Make sure to thank them yourself if you stop in.


The Field Strip

Parts List

  1. Barrel
  2. Mantle
  3. Frame
  4. Bolt
  5. Locking Block
  6. Takedown Catch


1. Remove the magazine from the pistol and check that the chamber is empty.  Safety First!






2. Grip the Frame in one hand and push back on the Mantle and Barrel and hold.

3. Turn the Takedown Catch 90 degrees clockwise.






4. Ease the Mantle and Barrel off the front of the frame.







5. Remove the Bolt from the Mantle.







6. Lift the Locking Block from the Mantle.

Your Lahti m/40 is now field stripped.  Reassembly is just the reverse.  The Locking Block has a front and back, there should be an arrow stamped on the bottom to specify.  Point this at the front of the gun.



Complete Strip

CAUTION The Swedish Lahti is a fairly complicated pistol with some small parts.  Most of the assembly is held by pins and they may or may not be flared depending on who has used the gun before.  Moreover, some pieces are riveted or heavily flared in place and should not be removed unless necessary for replacement.  Our pistol was a donor from the good folks at East Coast Guns of Summerville, SC, so we skipped a few risky steps.  Our apologies for those pictures that will be missing.

Parts List

  1. Front Sight
  2. Mantle
  3. Accelerator
  4. Accelerator Retainer Spring
  5. Accelerator Retainer
  6. Ejector
  7. Extractor
  8. Bolt
  9. Firing Pin
  10. Firing Pin Spring
  11. Firing Pin Cross-pin
  12. Recoil Spring
  13. Frame
  14. Trigger
  15. Trigger Bar Pin
  16. Trigger Bar
  17. Takedown Catch Spring
  18. Takedown Catch
  19. Trigger Pin
  20. Magazine Catch
  21. Magazine Catch Spring
  22. Hammer Spring and Plunger
  23. Hammer Pin
  24. Hammer
  25. Sear and Spring
  26. Sear Pin
  27. Grip
  28. Grip Screw
  29. Safety Lever
  30. Magazine Catch Pin
  31. Trigger Spring
  32. Locking Block


1. Pick up the Bolt.  Use a small screwdriver or punch to push the Extractor away from the Bolt‘s main body.  Then pull the Extractor out towards the front of the Bolt to remove.




2. Drift out the Firing Pin Cross-pin.

3. Tip out the Firing Pin and Firing Pin Spring. You may now set aside the Bolt and its components.



4. Accelerators have a slight variance by model.  In all cases there is a retaining pin under spring pressure.  Pickup the Mantle.  Depress the Accelerator Retainer and hold.

5. Remove the Accelerator by pulling it out and towards the back of the MantleCAUTION The Accelerator Retainer is under pressure and may be lost.  Remove slowly and carefully to keep it under control.

6. Use a small punch or screwdriver to fish out the Accelerator Retainer Spring.

7.  The Ejector is very sensitive and should only be removed if necessary.  Look inside the Mantle and depress the rear tab of the Ejector.  Then push it forward until it clears its recess.  You may now remove it from the outside of the Mantle.  You may also set aside the Mantle and its components now.


8. Pickup the Frame and locate the Safety Lever at the rear.  Insert a punch or screwdriver with the closest possible diameter into the hole at the front of the Safety Lever.

9. Carefully pry the Safety Lever as you turn it rearward.  At the rear of its intended sweep there is a stud.  Lift it just over this stud.


10. Stop the Safety Lever at this rearward position and lift it out of the Frame




11. Unscrew the Grip Screws and remove the Grips by lifting the bottom first.





12. Place a free finger on the Hammer and restrain it while pulling the Trigger.  Then ease the Hammer forward.




13. Drift out the Hammer Pin.  It may help to keep some pressure on the Hammer while doing so.




14. Use a tool to disengage the Hammer from the Hammer Spring.


15.  Now remove the Hammer.  Step 14 helped get around the permanently attached Recoil Spring easier.


16. Drift out the Sear Pin and remove the Sear and Spring.  You may need to pull the Trigger back to free it.

17. Remove the Hammer Spring and Plunger.



18. Locate the Trigger Spring and disengage it from the Trigger Bar.  It should stay attached to the Frame and should not be removed unless necessary.  If so, simply unwind it like a key ring.




19. Drift out the Takedown Catch.

20. You may remove the Takedown Catch Spring by placing a punch in the hole located at the front of the Frame and driving it rearward.

21.  The Trigger Bar Pin is usually riveted or heavily flared into place.  It is not recommended that you remove this component unless necessary.  If so, drift it out of place.  Then remove the Trigger Bar rearward and proceed to step 22.

22. This step is only necessary if you opted for step 21.  Drift out the Trigger Pin and remove the Trigger by pulling it down and rotating it out.

23. Drift out the Magazine Catch Pin.  Tap the Magazine Catch and the Magazine Catch Spring out of the Frame.

24. The Hold Open Latch is secured by a delicate spring.  Remove only if necessary.  We have not opted to do so on our loaner and can only provide written help.  If you need to remove it read steps 25 and 26 else skip to 27.

25. Use a small tool to push the rear of the Hold Open Latch Spring up.  Then lift it out of place.

26. Turn the Hold Open Latch up to about 90 degrees and then move it towards the right of the gun to remove.

27. The Front Sight should not be removed if unnecessary.  If so, drift it out of place left or right.


Your Lahti m/40 is now stripped.  Reassembly is just the reverse.  We recommend using a small bit of rolled paper or wood skewer to realign the Magazine Catch and Magazine Catch Spring as you place them in the Frame.


4 Responses to “Disassembly: Lahti m/40”

  1. David binkley says:

    My Swedish lahti will only allow me to pull the slide back a small way. What do I need to do?

    • Othais says:

      I’m afraid that is a bit too vague to troubleshoot from here. You may want to check with a gunsmith.

      • Derek Smith says:

        My specimen I purchased did not allow the bolt to be retracted at all. What ended up happening was the plunger was rusted to the frame not allowing the hammer to be cocked thus preventing the bolt from being pulled back.

        This write up was more than helpful albeit it did take many hours mostly trying to figure out how everything worked.

  2. Greg Hanson says:

    Very nice article with great pictures and clear instructions. Just what I needed, broke the Ejector on my Swedish M/40. I have put a lot of rounds in her over the years and this was the first problem. As a long time C&R shooter I found your web site a very valuable resource. Thank you.

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