7.5 cm Leichtgeschütz 40

Infobox Weapon
name=7.5 cm Leicht Geschütz 40


caption=Rear view of the LG 40
origin=Germany
type=Recoilless gun
is_ranged=yes
is_artillery=yes
service=1941-1945
used_by=Germany
wars=World War II
designer=
design_date=
manufacturer=Rheinmetall
production_date=1941-1944
number=450
variants=
weight=145 kg (319 lbs)
length=0.75 m
part_length=458 mm L/15.5
width=
height=
crew=
cartridge=
caliber=75 mm (2.95 in)
action=
rate=8 rpm
velocity=350 m/s (1,148 fps)
range= 6,800 m (7,434 yds)
max_range=
feed=
sights=
breech=horizontal sliding block
recoil=
carriage=
elevation=-15° to +42°
traverse=360° below 20° elevation
60° above 20° elevation

Development of recoilless weapons by Rheinmetall began in 1937 in an effort to provide airborne troops with heavy support weapons that could be dropped by parachute. Both Krupp and Rheinmetall competed for production contracts in a competition that was won by the latter. Initially produced under the designation of LG 1, this was soon changed to LG 40 to match the current 'year of origin' naming system.

Design Issues

One characteristic common to all the German recoilless guns was that they used ordinary shells, albeit with different cartridge cases to cater to the unique issues involved in with the recoilless principles. This gun used the HE shells from the 7.5 cm "Gebirgsgeschütz" (Mountain Gun) 36 and the anti-tank shell of the 7.5 cm FK 16 nA (Field Cannon, New Model). This meant that its ammunition couldn't be optimized to benefit from the peculiar ballistic characteristics of recoilless weapons. On the other hand it saved considerable research time and effort and meant that existing production lines and stocks of shells could be utilized at a considerable savings in resources.Two problems became evident after the "Leichtgeschütz" (light gun) was fielded. The gas expelled through the venturi of the firing mechanism could cause fouling in the mechanism itself, but fixing this required a redesign of the entire breech and was deemed not worth disrupting the production line or rebuilding the existing guns. The second problem was more serious in that the mounting began to shake itself apart after about 300 rounds were fired. This was principally caused by the torque imparted to the mount when the shell engaged the rifling as well as by the erosion of the nozzles by the combustion gases. These could be countered by welding vanes inside the nozzles that were curved in a direction opposite to the rifling which would then counteract the torque exerted by the shell and minimizing the stress on the gun mount.

Operational Use

The LG 40 first saw use during the Battle of Crete where it apparently equipped 2. Batterie/Fallschirmjäger-Artillery-Abteilung (2nd Battery/Parachute Artillery Battalion) [cite journal |last=Mündel |title=Der >>Igel<< von Rethymon, Fallschirmartillerie im Einsatz auf Kreta |journal=Der Deutsche Fallschirmjäger |year=1971 |month=April/May |pages=10–11 ] . It saw widespread use by German parachute units, both Luftwaffe and Waffen-SS for the rest of the war. The 500th SS-Fallschirmjäger Batallion used 4 during its airdrop on Tito's headquarters at Drvar.

The German Gebirgsjäger (mountain infantry) also appreciated its light weight and used a number of them during the battles in the Caucasus Mountains during the Summer and Fall of 1942.

References

Englemann, Joachim and Scheibert, Horst. "Deutsche Artillerie 1934-1945: Eine Dokumentation in Text, Skizzen und Bildern: Ausrüstung, Gliderung, Ausbildung, Führung, Einsatz". Limburg/Lahn, Germany: C. A. Starke, 1974Hogg, Ian V. "German Artillery of World War Two". 2nd corrected edition. Mechanicsville, PA: Stackpole Books, 1997 ISBN 1-85367-480-X