A powered square baler is operable to form a bale by compressing loose material. The powered square baler broadly includes a chassis and a reciprocating plunger assembly. The chassis includes a baler frame that presents a baling chamber to receive the loose material. The reciprocating plunger assembly includes a plunger head and an energy storage device. The plunger head is slidably mounted relative to the frame and is operable to be driven by a power source to reciprocate into and out of the chamber and apply a compressive force against the loose material. The energy storage device stores energy from the power source and transmits the energy to the plunger head in response to the applied compressive force, with the transmitted energy causing an impulse force to be applied against the loose material by the plunger head.