| 15 cm sIG 33 | |
| Origin: | Weimar Republic |
| Type: | Heavy infantry gun |
| Is Ranged: | yes |
| Is Artillery: | yes |
| Service: | 1927–1945 |
| Used By: | Nazi Germany |
| Wars: | World War II |
| Designer: | Rheinmetall |
| Design Date: | 1927–33 |
| Manufacturer: | Rheinmetall, AEG-Fabriken, Bohemisch Waffenfabrik |
| Production Date: | 1936–1945 |
| Number: | around 4,600 |
| Variants: | sIG 33/1 |
| Weight: | 1800kg (4,000lb) |
| Length: | 4.42m (14.5feet) |
| Part Length: | 1.65m (05.41feet) L/11 |
| Width: | 2.06m (06.76feet) |
| Cartridge: | cased separate-loading (6 charges) |
| Caliber: | 149.1mm |
| Rate: | 2-3 rounds per minute |
| Velocity: | 240m/s (HE) |
| Range: | 4700m (15,400feet) |
| Sights: | Rblf36 |
| Breech: | horizontal sliding-block |
| Recoil: | hydro-pneumatic |
| Carriage: | box trail |
| Elevation: | 0° to +73° or -4° to +75° |
| Traverse: | 11.5° |
The 15 cm sIG 33 (schweres Infanterie Geschütz 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.[1]
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.
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 150kg (330lb), 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.
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 1000m (3,000feet), with the rod separating at about 150m (490feet). 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 | 38kg (84lb) | 8.3kg (18.3lb) amatol | |
| I Gr 38 Nb | Smoke | 40kg (90lb) | oleum/pumice | |
| I Gr 39 Hl/A | Hollow-charge | 25.5kg (56.2lb) | cyclonite/TNT | |
| Stielgranate 42 | Demolition | 90kg (200lb) | 54kg (119lb) amatol |