76mm OB-25
76mm regimental gun M1943 (OB-25)
Overview
76mm OB-25
A 76mm OB-25 infantry gun on public display in a museum in Poland as seen in 2018.
Source: Zala -
© CC BY-SA 4.0
Soviet Union - No. 106 plant in Khabarovsk (988 pcs)
5.122 during World War 2
76-мм полковая пушка обр. 1943 г / 76-mm regimental gun M1943
Description
Introduction
The OB-25 is a World War 2 era infantry gun of Soviet origin. There were various designs project with improved performance over the earlier M1927 infantry gun. When all proved to costly and complex to produce, the much simpler OB-25 was adopted as the 76.2mm Model of 1943 regimental gun. This replaced the earlier M1927 on the production line and was produced in two factories. Lead designer was Tsirulnikov, who was held at the research institute as a prisoner. Since the OB-25 re-used the same ordnance the requested improved firepower over the M1927 wasn't there. However, existing stocks of ammunition could be used, the mobility was improved and production of the carriage was harmonized with the 45mm M1942 anti-tank gun.
Design
The OB-25 combines the newer split trail carriage of the long barrel 45mm M1942 anti-tank gun with a slightly modified ordnance of the older M1927 infantry gun. As such the OB-25 has no firepower advantage over the M1927. Upside is that the existing ammunition in the supply system could be used in the OB-25. The OB-25 was normally used with an ammunition limber. This was mandatory for horse drawn usage and optional when towed by vehicles.
Mobility
OB-25 was used both as a horse drawn weapon and could be towed by light and medium trucks. A limber was required for horse drawn use, but was commonly used with vehicles as well. The gun is light enough to be manhandled in the field, providing some flexibility and survivability in combat. Maximum towed speed is 35 km/h on roads. This increased mobility is due to the newer carriage with suspension.
Firepower
The OB-25 has similar ordnance as the M1927 and fires the same range of ammunition. The OF-350A high explosive fragmentation shell has a maximum range of 4.2 km. Direct fire range against a 2 m tall target is 350 m. Test firings showed a marginal reduction in accuracy for the OB-25 compared to the M1927. The new 76mm BP-350A HEAT round could also be fired by the older M1927. This penetrates 100 mm of RHA. Later a less costly BP-353A HEAT shell was introduced, this penetrates 70 mm and has a lower muzzle velocity. Both HEAT round have a maximum range of 1 km. Although direct fire range against a 2 m tall target is only 400 m and 300 m respectively. Hitting moving vehicles was difficult due to short range and low muzzle velocity. The OB-25 proved easier to use at firing against vehicles than the M1927, but was still a poor choice in the anti-tank role.
Users
The OB-25 was used in large numbers in the later stages of World War 2. Firepower against infantry positions was deemed adequate, and was much better than 45mm anti-tank guns. Anti-armor capability was purely a last ditch effort. During the Cold War it was replaced by the 107mm B-11 recoilless rifle. The B-11 was lighter, easier to conceal, fired explosive ammunition at distances 2 km further away and armor penetration nearly quadrupled.
Media
76mm OB-25
76mm regimental gun M1943 (OB-25) on display in the Museum of Russian Military History in 2024.
Source: Museum of Russian Military History
Copyright: CC BY-SA 4.0
76mm OB-25
Rear view of a 76mm OB-25 infantry gun on public display in a museum in Poland as seen in 2018.
Source: Zala
Copyright: CC BY-SA 4.0
Limber for the OB-25
Limber for use with the 76mm regimental gun M1943 (OB-25) on display in a museum.
Source: Saiga20K
Copyright: CC BY-SA 3.0
Details
Related articles
45mm M1942
The OB-25 uses the same split trail carriage and limber as the 45mm M-42 anti-tank gun.
107mm B-11
The OB-25 was replaced during the early stages of the Cold War by the B-11 recoilless rifle.