Swedish Lahti M40 Pistol
By Vince Oliva

Finnish born Aimo Johannes Lahti (1896-1970) was a genius military firearms designer. Besides the pistol that bears his name, he also designed the combat proven Soumi M/ 1931 submachine gun and the M39 20mm Anti-Tank Gun. The Soumi M/1931 was so successful during the Winter War (also known as the Soviet- Finnish War or the Russo-Finnish War when Russia attacked Finland on November 30, 1939) that significant features were copied in the Soviet PPS-41submachine gun. The Swedish Lahti M40 pistol is the clone of the Finnish L35 Lahti. Some people would say it is a copycat of the Luger. The Lahti, however, is bigger, heavier and more angular in appearance. The action is completely different that attributes its reliability in extreme cold weather conditions; a virtue not normally attributed to the Luger.

The Finnish L35 in 9x19mm Parabellum was conceived in 1929 with the requirement that it would function reliably in the harsh Scandinavian winters. It was accepted by the Finnish armed forces in 1935 and saw action in the Russo-Finnish War (Winter War) of 1939-40. The Finnish company Valtion Kivaaritehdas (State Weapons Factory) at Jyvaskyla (VKT) manufactured the L35 from 1935 until 1958. AfterWWII the factory was renamed Valmet Oy Tourula (VKT). Total Finnish production was 12,000 guns. This pistol is very robust and an extremely reliable gun. However, due to its complicated design, it was nearly impossible to disassemble without the services of a gunsmith: but then again, no components were likely to break or wear. The only other drawback was that it was slightly too heavy.

The Swedish Army was in the market for a new pistol and purchased a small amount of German P38s. With WWII brewing, supply problems persuaded the Swedes to adopt the L35 because of its efficient performance in the Winter War. Sweden purchased the necessary license and designated the Finnish L35 as the M40.

Several differences are noted between the L35 and M40. Initial manufacture of the L35 was slow since the pistols were hand built. The L35 is a short-recoil operated, locked breech pistol. The bolt and barrel extension are interlocked by a vertically movable locking lug, which is cammed out of engagement when hitting the frame after short recoil. On the top of the barrel extension there is a loaded chamber indicator. The L35 has a bolt accelerator which gives the bolt extra energy to operate in extreme cold and dirt.

Between 1941 and 1946, the Swedish M40 was made by Husqvarna Vapenfabrinks A.B. (HVA). These guns had a larger trigger guard for winter gloves, no loaded chamber indicator and lacked the bolt accelerator whichdecreased reliability. The M40 also has the backstrap cut for a removable shoulder stock that is interchangeable with the Luger stock. Husqvarna, the sole manufacture, produced an estimated 82,480 M40s and 850 civilian models.

The M40 underwent many changes verses the L35. The first models producedwere exact copies of the L35, but the design changed throughout the production period. The first ones made had the loaded chamber indicator, but most of these were called back and had this feature removed, and a few incorporated small trigger guards. Barrels were also changed. Early ones have a ramped front sight base and round rear end. The later model has a straight base and a hexagon nut rear end and extended 35mm.

The nickel steel alloy that HVA wanted to use was scarce and wasn’t available to make the slides, barrel and frame out of it, so it was only used for the barrels. Because of this lack of nickel steel, cracks started to appear in the slides. HVA produced four types of slides to correct this problem, but due to the design changes, steel quality and the use of unsuitable ammunition, major problems continued. Sweden used m/ 39B steel jacketed ammo intended for use with submachine guns that created excessive high pressure, thus wearing out the gun. In a study made by the Swedish Army, service life of the M40 was estimated at 3,000 rounds using the m/39B cartridge.

As exterior finishes, the L35 was machined and polished more exquisite than the M40s. All Husqvarna grips are trademarked with the Husqvarna crowned logo and are made of plastic. The majority of Swedish issued Army pistol grips were brown, on other contracts, black.

The very first M40 serial numbers had “A” prefixes (rare). Swedish Air Force guns have the letter “F” and civilian with “H” prefixes. About 850 civilian model “H” serial numbered guns were produced and they had both small and large trigger guards. This occurred the same time the Swedish Army developed their requirements for a large trigger guard.

The Danish police ordered 10,000 M40s and the serial numbers were in the 5,000 to 15,000 range with a “D” prefix. Late in WWII the Swedes, who remained neutral, trained and partially equipped Danish and Norwegian officers and police in Sweden. 500 “neutral” (rare) versions of the M40 were “secretly” issued to the Norwegian resistance. The “neutral” M40s lacked the manufacture and inspector markings and the Husqvarna logo was ground off the grip plates. Serial numbers were between 31,500 and 32,000. The serial numbers were reportedly to be ground off also but this author cannot verify this as fact. The Danish company called V.Parbst bought scrapped M40s and some spare parts from the Danish government in 1970 and assembled a few guns with a serial number prefix of “VP” being VP1 to 19 and VP100 to 101. A Swiss gun dealer requested 20 pistols with personalized serial numbers to PS1 to 20.

Standard Army issue M40s had no prefix to the serial numbers and incorporated unit markings on the right ride plate. Swedish Proof marks are located on the rear frame below the slide while the civilian models and reportedly “neutral”guns had none. The M40 was in Swedish Army use until replaced by the Pistol M88/88B (Glock 17/19) in 1988.

Each issued M40 came with a leather holster, two extra 8-round magazines, cleaning rod and magazine loader/tool and oilier. The loader tool is also a flat head screwdriver. Because of the angle of the magazine, a high tensile strength spring is needed to feed the pistol with reliability. The magazine incorporates a small push down button, but without the loading tool, it is very hard on the thumbs. Early leather holsters were a smooth tanned brown and a much higher quality than the later black pebble texture.

The Swedish Lahti M40 takedown is relatively simple. For basic disassembly first remove the magazine and clear the chamber. Hold thebarrel extension back, or push the barrel against a hard surface, and atthe same time rotate the takedown latch. The barrel assembly is now slid forward. If not, you haven’t removed the magazine. After the barrel and barrel extension are free of the receiver, push the locking block up and withdraw the slide. When replacing the locking block, be sure the arrow on the underside of the block is facing forward toward the barrel. You should now have all the major parts disassembled.

The M40 is still a robust military firearm and very collectable. It is comfortable to shoot with low recoil due to its heavy weight and large “U” notched rear sight. There is no doubt with today’s lower pressure commercial ammo it would probably double or triple the service life.

This article first appeared in Small Arms Review V10N7 (April 2007)
and was posted online on December 7, 2012


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