7.5 cm L/45 M/32 anti aircraft gun

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7.5 cm L/45 M/32
Three view drawing of the L/45 m/32 semistatic anti aircraft gun.
Type	Anti aircraft gun
Place of origin	Norway
Service history
In service	1936 - 1940
Used by	Norway
Wars	World War II
Specifications
Weight	??
Barrel length	45

Shell	HE and shrapnel
Caliber	75 mm
Carriage	Mobile / semistatic
Rate of fire	??
Muzzle velocity	750 m/s
Effective range	m

The 7.5 cm L/45 M/32 anti aircraft gun was designed and manufactured in Norway in the 1930s. The mount was an unusual design, having a platform with three outriggers instead of the usual four. Its main use was for positional air defense of important cities and installations.

1 Background and design
2 Service history and fate
3 See also
4 References

[edit] Background and design

Around 1930 it became clear that a more modern anti aircraft gun than the M/16, which had been designed in the later half of World War I. A number of 76 mm anti aircraft guns had been bought from Bofors in 1928, but were no more modern than the M/16.

In 1932 a new and innovative anti aircraft gun was designed. Partly based on the M/16, it was mounted on a lowslung trailer with three outriggers. Two of the outriggers would fold together for transport, and two rubber wheels could be mounted. The outriggers could be adjusted somewhat in elevation to help place the mount in a horizontal position. The mount allowed for a 360° traverse and an elevation between 0° and 85°. It was equipped with a muzzlebrake to reduce recoil, a hydro-pneumatic recoil cylinder and a gas cylinder to aid the forward movement of the barrel at high elevations. In addition the mount had two heavy springs to counterbalance the barrel, since the entire barrel was mounted ahead of the pivots. The barrel was 45 calibers long and had 28 rifles twisting to the right, just like the M/16's barrel. Also similar, if not identical, to the M/16 was the breech block; a semi automatic horizontal wedge that the gunner had to manually open it to remove the case from the previous shoot, but which closed automatically on insertion of a new round.

Like late models of the M/16, the M/32 was equipped to receive gun-laying information from a central sight. The gun was also equipped with a device for automatically adjusting the time fuses on the shells.

[edit] Service history and fate

The M/32 was first issued to units of the Norwegian Army in 1936, and proved a popular weapon. First used at the anti aircraft school based at Stavern, guns was also issued to the units responsible for defending Oslo and Raufoss. It remained in Norwegian service until the Germans invaded Norway on 9 April 1940.

At Raufoss, a total of four M/32 was installed in two batteries. After observing several airplanes out of range for the guns, one of the batteries was sendt to Elverum to protect the Parliament and the King. These two guns was rather destroyed and left behind when the battery retreated. The remaining two gun battery at Raufoss fired at aircraft in the evening of the 9th, with no visible result. After several days the battery was moved to Dombås, where one of the guns was damaged while being set up. At Dombås the last M/32 was used to engage German paratroopers on the ground, leading to the surrender of the German force, as well as shooting against German bombers with unknown results.

In Oslo, the M/32 was installed in four batteries of three guns each. The batteries was well equipped - by contemporary Norwegian standars - with central sights, range and heightfinders. When the Germans attacked Oslo, the batteries all took part in the defensive battle. Despite a multitude of problems - lack of ammunition, unreliable fuses, electrical batteries that discarged too quickly, central sights that fell apart due to the shockwaves from the fireing, lack of training and more - the batteries claimed to have shoot down five or six German aircraft. After reviewing the Luftwaffe's own reports and the number of wrecked aircraft in Oslo area on April 9th researchers have however concluded that a single shoot-down is the most likely number of German aircraft shot down by any form of ground based air defence that day. A not insignificant number of aircraft were it, some very seriously, but only one seems to have crashd as a result. The batteries and the guns were abandoned when Oslo surrendered due to the treat of German bombing of civilians.

The fate of the M/32s after the Germans captured Norway is unknown, but it must be assumed that the Germans used them for air defence in Norway. Today one is preserved at the Armed Forces Museum in Oslo.