15 cm sIG 33

The 15 cm sIG 33 (schweres Infanteriegeschütz 33, lit. "heavy infantry gun") was the standard German heavy infantry gun used during Second World War. It was the largest weapon ever classified as an infantry gun by any nation.

15 cm sIG 33
A sIG 33 at the Belgrade Military Museum, Serbia
Type	Heavy infantry gun
Place of origin	Weimar Republic
Service history
In service	1927–1945
Used by	Nazi Germany
Wars	World War II
Production history
Designer	Rheinmetall
Designed	1927–33
Manufacturer	Rheinmetall, AEG-Fabriken, Bohemisch Waffenfabrik
Produced	1936–1945
No. built	around 4,600
Variants	sIG 33/1
Specifications
Mass	1,800 kg (4,000 lb)
Length	4.42 m (14 ft 6 in)
Barrel length	1.65 m (5 ft 5 in) L/11
Width	2.06 m (6 ft 9 in)
Shell	cased separate-loading (6 charges)
Caliber	149.1 mm (5.87 in)
Breech	horizontal sliding-block
Recoil	hydro-pneumatic
Carriage	box trail
Elevation	0° to +73° or -4° to +75°
Traverse	11.5°
Rate of fire	2-3 rounds per minute
Muzzle velocity	240 m/s (790 ft/s) (HE)
Effective firing range	4,700 m (5,100 yd)
Sights	Rblf36

Its weight made it difficult to use in the field, and the gun was increasingly adapted to various ad hoc mobile mounting, which were generically referred to as the SIG 33.

Development

Sources differ on the development history, but the gun itself was of conventional design. Early production models were horse-drawn, with wooden wheels. Later production models had pressed steel wheels, with solid rubber tires and air brakes for motor towing, albeit at a low speed (only carriages with pneumatic tires and suspension system could be towed at highway speeds). As with most German artillery carriages, the solid rubber tires and lack of springing meant that the gun could not safely be towed above 10 mph, and horse-drawing was still extensively employed.

The sIG 33 was rather heavy for its mission, and it was redesigned in the late 1930s to incorporate light alloys. This saved about 150 kg (330 pounds), the outbreak of war forced the return to the original design before more than a few hundred were made, as the Luftwaffe had a higher priority for light alloys. A new carriage, made entirely of light alloys, was tested around 1939, but was not accepted for service.

Artillerymen of the Großdeutschland Division loading a sIG 33

Ammunition

Most of the shells used by the sIG 33 were unexceptional in design. The Stielgranate 42 was an exception. The finned projectile was mounted in front of and outside the barrel on a muzzle-loaded driving rod, and fired with a special propellant charge. The projectile had a range of about a 1,000 metres (1,100 yd), with the rod separating at about 150 metres (160 yd). The Stielgranate 42 was designed for demolition and obstacle clearance, unlike the previous anti-tank Stielgranate 41.

Shell	Type	Weight	Filler
I Gr 33	HE	38 kilograms (84 lb)	8.3 kilograms (18 lb) amatol
I Gr 38 Nb	Smoke	40 kilograms (88 lb)	oleum/pumice
I Gr 39 Hl/A	Hollow-charge	25.5 kilograms (56 lb)	cyclonite/TNT
Stielgranate 42	Demolition	90 kilograms (200 lb)	54 kilograms (119 lb) amatol

See also

• SIG 33 Self-Propelled Artillery
• 152 mm mortar M1931 (NM)

References

• Chamberlain, Peter, and Hilary L. Doyle. Thomas L. Jentz (Technical Editor). Encyclopedia of German Tanks of World War Two: A Complete Illustrated Directory of German Battle Tanks, Armoured Cars, Self-propelled Guns, and Semi-tracked Vehicles, 1933–1945. London: Arms and Armour Press, 1978 (revised edition 1993). ISBN 1-85409-214-6
• Engelmann, Joachim and Scheibert, Horst. Deutsche Artillerie 1934–1945: Eine Dokumentation in Text, Skizzen und Bildern: Ausrüstung, Gliederung, Ausbildung, Führung, Einsatz. Limburg/Lahn, Germany: C. A. Starke, 1974
• Gander, Terry and Chamberlain, Peter. Weapons of the Third Reich: An Encyclopedic Survey of All Small Arms, Artillery and Special Weapons of the German Land Forces 1939-1945. New York: Doubleday, 1979 ISBN 0-385-15090-3
• Hogg, Ian V. German Artillery of World War Two. 2nd corrected edition. Mechanicsville, PA: Stackpole Books, 1997 ISBN 1-85367-480-X
• Trojca, Waldemar and Jaugitz, Markus. Sturmtiger and Sturmpanzer in Combat. Katowice, Poland: Model Hobby, 2008 ISBN 978-83-60041-29-1
• Infanteriegeschütze : lexikon-der-wehrmacht.de (German)
• 15-cm Heavy Infantry Howitzer, German Infantry Weapons, Military Intelligence Service, Special Series No. 14, May 25, 1943.