A baler for use with a forming bale (186) having a first bale attribute. The baler including a frame (14), and a compression system (26) coupled to the frame (14) where the compression system (26) at least partially defines a compression chamber (96) sized to receive at least a portion of the forming bale (186) therein. The baler also includes a feed pan (66, 66') at least partially defining a pre-compression chamber (70, 70'), and where the shape of the pre-compression is adjustable, and where the pre-compression chamber (70, 70') is open to the compression chamber (96). The baler also includes a sensor (334, 338, 342, 346, 378a, 378b, 378c, 378d) configured to output signals representative of the first bale attribute, and a controller (322) in operable communication with the feed pan (66, 66') and the sensor (334, 338, 342, 346, 378a, 378b, 378c, 378d), and where the controller (322) is configured to actively adjust the shape of the pre-compression chamber (70, 70') based at least in part upon the first bale attribute of the forming bale (186).
