The M107 self-propelled gun was a 175-mm artillery piece employed by the US Army during the Vietnam War. It was also used by foreign armies in the Iran-Iraq War and the Yom Kippur War in 1973. Essentially, it was a 175-mm-caliber heavy howitzer mounted on a tracked chassis, which was powered by a 450-HP General Motors, 8-cylinder, super-charged, diesel engine. It entered service in 1962 and was phased out at the end of the Cold War. The M107 self-propelled gun shared the same chassis of the 203-mm M110.
The howitzer of the M107 had a long barrel, which fired shells to the maximum distance of 32.8 km. It was very useful to provide fire support against bunkers and pillboxes. It was also used as a counter-battery weapon, due to the fact to its long range. In contrast to the M109 self-propelled howitzer, the M107 did not have a turret. Therefore, the crew was unprotected. However, they had more space; this fact allow the men who served it to load the breech faster, with a faster rate of fire. Although it was fitted with a hydraulically-operated loader, in combat situations in Vietnam it was never used, because it was faster to load by hand by skilled soldiers.
Specifications:
Type: self-propelled heavy howitzer
Weight: 28.5 tons
Barrel Length: L/60
Caliber: 175-mm
Shell: separate charge loading.
Breech: interrupted screw
Elevation: -5 to +65 degrees
Traverse: 60 degrees (hydraulically-operated)
Gun Range: 32.8 km
Vehicle Range: 720 km
Maximum Speed: 80 km/h on road.
Below, the M107 self-propelled howitzer in Vietnam
Official technical demonstration of the M107 (video)