A shoring device is disclosed comprising a piston and a cylinder. The piston is axially expanded by compressed gas, whereby the shoring device engages two opposing surfaces. An outer cam collar and a concentrically enclosed inner ring are mounted upon the cylinder end into which the piston inserts. This outer cam collar comprises at least two cam edges, two stop faces and a threaded cam pin within an integral boss. The inner ring comprises a continuous circular indentation as well as a continuous circular inner lip. The outer cam collar and inner ring, together with the continuous circular inner lip and threaded pin, firmly retain the piston. These piston retention features prevent inadvertent rotation and collapse of the piston during use.