"The M110 is armed with a 203 mm (8 inch) M2A2 howitzer in an M158 mount and has an elevation of +65°, a depression of -2° and a traverse of 30° left and right. Elevation, depression and traverse are hydraulic with manual controls for emergency use. The weapon has a hydropneumatic recoil system, an interrupted screw breech block and a percussion firing mechanism. Mounted at the rear of the chassis on the left side is a rammer and loader assembly which lifts a projectile from the rear or left side of the vehicle, positions it and rams it into the chamber. Hydraulic power for operating the system is obtained from the vehicle's system but it can also be operated by handcranks. Mounted at the rear of the chassis is a large hydraulically operated spade that is lowered into position before firing begins."
Source: http://www.army-guide.com/eng/product1778.html