An agricultural baler (10) includes a main bale chamber (26) extending in a bale forming direction (102) from an inlet end (104) to an outlet end (32). The main bale chamber (26) includes a plurality of stationary walls (106, 110, 112) and a plurality of movable density doors (120) positioned downstream from the stationary walls (106, 110, 112), relative to the bale forming direction (102). The stationary walls include a ceiling (106), a first side wall (110) and a second side wall (112). A plunger (30) compresses and moves the crop material from the inlet end (104) towards the outlet end (32) of the bale chamber (26). The baler (10) is characterized in that the first side wall (110), the second side wall (112) and/or the ceiling (106) comprises a constriction surface (100, 130), which constricts the main bale chamber (26) in a direction transverse to the bale forming direction (102).
