A motorized caulk gun has a housing which receives a plunger. The plunger is disposed adjacent to caulk cartridge which is received in the housing. The plunger is movable in a first direction to discharge caulk from the cartridge. A first and second plate moves the plunger rod in a direction to squeeze caulk from the cartridge. A first and second cam act on the plates via a cam follower such that the plates alternately engage the plunger rod to drive it in a forward direction to squeeze caulk from the cartridge.