M40 75mm recoilless gun

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Daniel L
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M40 75mm recoilless gun

Post by Daniel L » 08 Oct 2002 02:24

I know that there are very little info about this weapon so I thought that maybe we could try to put assemble some information about it.

I once read that soldiers who used this gun used mud and earth to save their ears from the pressure effects caused by the gun.

Image
The best picture I could find of the gun.

regards
Last edited by Daniel L on 08 Oct 2002 12:08, edited 3 times in total.

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Mait
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Post by Mait » 08 Oct 2002 06:31

For a picture, try this:

http://ww2.ee/army/germany/arty/75mm_1940/pics.shtml

On that site, there is an article about that gun (but it is in Russian).

Best Regards,

Mait.

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Daniel L
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Post by Daniel L » 08 Oct 2002 11:34

Thanks Mait. I'll translate the article and post it later. I wonder if Volstad didn't know that the wheels were stripped when the gun was in its firng position? Here are the pictures from the article:

Image

Image
In firing position.

regards

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Robert Hurst
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M40 75mm Recoilless Gun (7.5cm Leicht Geschutz 40 "Olmu

Post by Robert Hurst » 08 Oct 2002 14:57

Hi Charlie

The LG 40 was built in four parts, each capable of parachute decent without the need for special packing; the ordnance split into barrel and breech assembly, while a simple top carriage and a wheeled tripod assembly formed the rest of the equipment.

Although Rheinmetal were responsible for the basic research, both they and Krupp were given development contracts and both produced prototypes. The Krupp model used a simple side-swinging breech mechanism and was mounted on two motorcycle wheels, while the Rheinmetall type used a horizontal sliding breechblock and two small aircraft-type wheels.

The latter was the one accepted for service. Extensive use was made of light alloy in the mounting to save weight; and, to prevent the back blast from ricocheting on to the detachment, the elevation and traverse gears were interconnected so that the normal 360 degrees traverse was restricted to 30 degrees each way as soon as the elevation reached 20 degrees.

The firing mechanism was placed in a streamlined housing in the centre of the jet venturi, so that a normal type primer in the centre of the plastic case base could be used.

The danger area at the rear of the gun extended to 100 m (109 yds) for practice firing ot 50 m (55 yds) for combat firing; this, however, referred only to the actual jet blast, and stones and debris were disturbed some considerable distance beyond this. Firing instructions also emphasised the danger to the detachment members' ears from the blast, and recommended them to plug their ears tightly with clay or mud before firing. A total of 450 of these guns were made, 170 by Rheinmetall-Borsig at Dusseldorf.

Data

Calibre: 75 mm (2.95 in).
Length of gun: 750 mm (29.53 in).
Length of bore: 458 mm (18.03 in).
Rifling: 28 grooves, uniform right-hand twist, 1/52.
Breech mechanism: horizontal sliding block, percussioin fired.
Traverse: 360 degrees below 20 degrees elevation, 60 degrees above 20 degrees elevation.
Elevation: -15 degrees to + 42 degrees.
Weight in action: 145 kg (320 lb).

Performance:

Firing standard high explosive shell weighing 5.83 kg (12.86 lb).

Full charge: velocity 350 m/ps (1,148 ft/ps), maximum range 6,800 m (7,434 yds).

Ammunition:

Separate-loading, cased charge.

Projectiles:

7.5 cm Gr 34 A1: fuzed K1 AZ 23, weight 5.75 kg (12.68 lb).
This was an high explosive shell, filled with a 90/10 mixture of TNT and aluminium powder.

7.5 cm Gr 38 H1/B: fuzed AZ 38, weight 4.40 kg (9.70 lb).
This is a hollow charge anti-tank shell.

These were the shells fired by the 7.5 cm Geb G.36.

7.5 cm Pzgr. rot: fuzed Bd Z f 7.5 cm Pzgr, weight 6.08 kg (14.99 lb).

This was an armour piercing high explosive shell of conventional pattern.

This was the shell fired by the 7.5 cm F K 16 nA.

Propelling charge

The charge consisted of a silk-cloth bag containing 1.21 kg (2.68 lb) of Digl Str P with a gunpowder igniter stitched to the bottom; this was carried in a cartridge case with an 85 mm (3.35 in) aperture in the base that was closed by a plastic disc. A percussion primer C/43 was screwed into the centre. The case-mouth was closed by a cardboard cup.

Regards

Bob

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Daniel L
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Post by Daniel L » 08 Oct 2002 14:58

This is my translation, there are probably some errors left, pm me if you find any big errors.

The design of the 75mm light gun relates to the recoilless rifles, in the breech of its stem is a nozzle for the release of solid-reactant gases outside, i.e., to the side, opposite to the direction of the motion of projectile. In this case the dynamic balancing occurs - stem with the shot remains fixed, thanks to which it is possible to forego the bulky and heavy antigravity devices. The development of recoilless rifles began in Germany in the middle thirties. They were necessary in order to ensure artillery for the fallschirmjägers, they were called "light weapons" due to secrecy. One such weapon is the 75- mm light gun, which was being used in the parachute divisions of the Wehrmacht against infantry targets and weapon emplacements. the first succesful use of the weapon was in the combat during the large-scale airborne operation on the seizure of Crete island in the spring of 1941.

The guns consists of following major portions: stem with the lock and the nozzle, upper machine tool with lift and swivel gears of guidance, lower machine tool with the tripod and tread with the cushioning of the sight mechanisms. The gun barrel consists of pipe- monoblock and breech, connected to the pipe with the aid of the sukharnogo lock. The lock is horizontal, wedge, which is opened/disclosed to the right. In the wedge of lock are openings for the release of the solid-reactant gases resultant with the shot back; the nozzle is fixed on the wedge. The upper machine tool poured from the light alloy revolves on the pintle of lower machine tool. Sectorial type lift and swivel gears are assembled on the upper machine tool. Lower machine tool consists of base, three feet and tread. Feet are hinged connected with the base of lower machine tool. In the firing position they are fixed with the aid of the stops. Rear feet are connected together upon transfer to the march position, and the nose wheel strut rises and is attached to the clip of stem. The tread consists of the tubular axle, in which is assembled torsion cushioning, and two disk wheels with the continuous rubber tires. The weight of gun in the firing position is 145 kg. For the landing by parachute method and for transportation on the drag harrows under the winter conditions the gun is divided into two parts (stem and gun carriage). The light weight of system gives a good maneuverability on the field of battle. The gun can conduct fire at the elevation from - 15° to 42° with the sector of horizontal field of fire 60°, and at the elevation from - 15° to 20° - with the sector of horizontal field of fire 360°. In this case is ensured the maximum range of shooting 8 100 meter. Ammunition to the 75 mm gun consists of special fixed rounds with the HE fragmentation, cumulative and armor-piercing shells. Case used in these cartridges has a bottom of plastic with the nest for primer cup. The bottom of the case flies out when firing and thus it makes it possible for the part of solid-reactant gases to leave back through the nozzle. The HE fragmentation projectile with a weight of 5,7 kg has the initial velocity of 376 m/s, shooting is conducted on the distance of 8 100 m. The shaped-charge shell with a weight of 4,6 kg has an initial velocity of 364 m/s and a firing distance 6 800 m. It is capable to penetrate armor with a thickness of 50 mm. As all recoilless rifles the 75- mm gun possesses such deficiencies as the disclosing action of the solid-reactant gases, which emerge from the nozzle, the presence from behind of the nozzle is hazardous zone as deep as 50 m, and also the outgoing of the nozzle gases produces a strong sound, which can damage the eardrums.

The caliber of 75 mm
Initial velocity of projectile: 376 m/s (HE fragmentation) 364 (cumulative)
The greatest angle of elevation: 42 degrees angle of depression -15 angle of the horizontal
Field of fire: 60 degrees
The weight when emplaced: 145 kg
Rate of fire: 8 shots/min
Maximum range of shooting: 6 800 - 8 100 m
Armor-piercing ability with shaped-charge shells: 50 mm

regards

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Robert Hurst
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M40 75mm Recoilless Gun (7.5cm Leicht Geschutz 40 "Olmu

Post by Robert Hurst » 08 Oct 2002 14:58

Hi Charlie

The LG 40 was built in four parts, each capable of parachute decent without the need for special packing; the ordnance split into barrel and breech assembly, while a simple top carriage and a wheeled tripod assembly formed the rest of the equipment.

Although Rheinmetal were responsible for the basic research, both they and Krupp were given development contracts and both produced prototypes. The Krupp model used a simple side-swinging breech mechanism and was mounted on two motorcycle wheels, while the Rheinmetall type used a horizontal sliding breechblock and two small aircraft-type wheels.

The latter was the one accepted for service. Extensive use was made of light alloy in the mounting to save weight; and, to prevent the back blast from ricocheting on to the detachment, the elevation and traverse gears were interconnected so that the normal 360 degrees traverse was restricted to 30 degrees each way as soon as the elevation reached 20 degrees.

The firing mechanism was placed in a streamlined housing in the centre of the jet venturi, so that a normal type primer in the centre of the plastic case base could be used.

The danger area at the rear of the gun extended to 100 m (109 yds) for practice firing ot 50 m (55 yds) for combat firing; this, however, referred only to the actual jet blast, and stones and debris were disturbed some considerable distance beyond this. Firing instructions also emphasised the danger to the detachment members' ears from the blast, and recommended them to plug their ears tightly with clay or mud before firing. A total of 450 of these guns were made, 170 by Rheinmetall-Borsig at Dusseldorf.

Data

Calibre: 75 mm (2.95 in).
Length of gun: 750 mm (29.53 in).
Length of bore: 458 mm (18.03 in).
Rifling: 28 grooves, uniform right-hand twist, 1/52.
Breech mechanism: horizontal sliding block, percussioin fired.
Traverse: 360 degrees below 20 degrees elevation, 60 degrees above 20 degrees elevation.
Elevation: -15 degrees to + 42 degrees.
Weight in action: 145 kg (320 lb).

Performance:

Firing standard high explosive shell weighing 5.83 kg (12.86 lb).

Full charge: velocity 350 m/ps (1,148 ft/ps), maximum range 6,800 m (7,434 yds).

Ammunition:

Separate-loading, cased charge.

Projectiles:

7.5 cm Gr 34 A1: fuzed K1 AZ 23, weight 5.75 kg (12.68 lb).
This was an high explosive shell, filled with a 90/10 mixture of TNT and aluminium powder.

7.5 cm Gr 38 H1/B: fuzed AZ 38, weight 4.40 kg (9.70 lb).
This is a hollow charge anti-tank shell.

These were the shells fired by the 7.5 cm Geb G.36.

7.5 cm Pzgr. rot: fuzed Bd Z f 7.5 cm Pzgr, weight 6.08 kg (14.99 lb).

This was an armour piercing high explosive shell of conventional pattern.

This was the shell fired by the 7.5 cm F K 16 nA.

Propelling charge

The charge consisted of a silk-cloth bag containing 1.21 kg (2.68 lb) of Digl Str P with a gunpowder igniter stitched to the bottom; this was carried in a cartridge case with an 85 mm (3.35 in) aperture in the base that was closed by a plastic disc. A percussion primer C/43 was screwed into the centre. The case-mouth was closed by a cardboard cup.

Regards

Bob

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Daniel L
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Post by Daniel L » 08 Oct 2002 15:09

You are a true asset Bob, thanks for the help. Are there any documented combat experiences with the gun, which units recieved it? I guess that we still have some questions to fill in on this amazing gun. Which source/s did you use for your post?

regards

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Daniel L
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Post by Daniel L » 08 Oct 2002 15:20

The German paratroops were equipped with the excellent 75-mm. and 105-mm. airborne recoilless guns; both had short barrels and carriages made of light metal alloy. In suitable terrain the 75-mm. gun could be easily drawn by two men, and its elevation was the same as that of the 37-mm. antitank gun of the Army. The maximum range was 3,850 yards for the 75-mm. gun and 9,000 yards for the 105-mm. gun. Both had the following disadvantages: a. A large amount of smoke and fumes was generated, and the flash toward the rear was visible at night for a great distance. b. They could be used only as flat-trajectory weapons. Attempts to use the airborne recoilless guns as high-angle weapons were not satisfactory. Moreover, in an airborne operation it was seldom possible to carry along the necessary amount of ammunition or have it brought up later. Thus, as a rule, only important point targets could be attacked with single rounds, generally from an exposed fighting position.

from: http://252.greatbooksonline.org/wwiiair/wwiiair2.htm

regards

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Robert Hurst
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M40 7.5 cm LG40 Recoilless Gun

Post by Robert Hurst » 14 Oct 2002 14:31

Hi Charlie

The info that I put on for the above weapon was taken from 'German Artillery of World War Two', by Ian V. Hogg, published in the UK by Greenhill Books, Lionel Leventhal Ltd, Park House, 1 Russel Gardens, London, NW11 9NN, ISBN 1-85367-261-0.

Their email address is http://www.sales@greenhillbooks.com

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Daniel L
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Post by Daniel L » 14 Oct 2002 14:38

Thanks, I know of it. The last time I was trying to buy it it was out of stock 'tough.

regards

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Robert Hurst
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Post by Robert Hurst » 14 Oct 2002 14:51

Hi Charlie

If you want any more info on German Recoilless guns, I'm more than happy to oblige.

Regards

Bob :D

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Daniel L
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Post by Daniel L » 14 Oct 2002 14:54

Thanks, you're always a great asset, thanks for the help!

regards

Mark V
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Post by Mark V » 14 Oct 2002 16:30

Some links on German LGs:

http://www.andreas-treptow.de/art_leg_75mm_80mm.htm

http://www.lexikon-der-wehrmacht.de/Waf ... chutze.htm (follow links to find pictures)

Both in german, sorry.

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Daniel L
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Post by Daniel L » 14 Oct 2002 17:18

Thanks mark, there's no problem for me with them being in german!

regards

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Juha Tompuri
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Post by Juha Tompuri » 14 Oct 2002 20:37

When were the german recoilless guns produced? Finland captured two russian 76,2mm recoilless guns at Winter War. After the war the other was sent to Germany. Wonder how much did it effect to the development of the German guns.

Juha

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