A screw for a plasticating apparatus, the screw comprising: a longitudinal axis, the screw being rotatably supportable in a barrel for rotation about the longitudinal axis, the screw having a core and at least one helical flight extending along a length of the screw, the helical flight extending in a first threaded direction and defining a first helical path having a first helix angle less than ninety degrees; the helical flight defining a helical channel; and a longitudinal portion of the screw having a plurality of advancing grooves with each advancing groove having at least one closed-end, the plurality of advancing grooves being arranged in a noncontinuous helix cut in the screw core in the helical channel of the screw, the plurality of advancing grooves forming a forward helical pathway in the helical channel for conveying material through the helical channel along the at least one helical flight, the advancing grooves being parallel to and having the same first helix angle as the helical flight; characterized in that the longitudinal portion further has a plurality of noncontinuous cross-cut grooves (37C, 37N) oriented in the first threaded direction common to that of the helical flight and/or in a neutral direction parallel to the longitudinal axis and traversing several of the plurality of advancing grooves; and at least one of: (a) at least one of the plurality of advancing grooves having an advancing groove depth taper including an increasing depth taper or a decreasing depth taper; and (b) at least one of the plurality of cross-cut grooves (37C, 37N) having a cross-cut groove depth taper. a longitudinal axis, the screw being rotatably supportable in a barrel for rotation about the longitudinal axis, the screw having a core and at least one helical flight extending along a length of the screw, the helical flight extending in a first threaded direction and defining a first helical path having a first helix angle less than ninety degrees; the helical flight defining a helical channel; and a longitudinal portion of the screw having a plurality of advancing grooves with each advancing groove having at least one closed-end, the plurality of advancing grooves being arranged in a noncontinuous helix cut in the screw core in the helical channel of the screw, the plurality of advancing grooves forming a forward helical pathway in the helical channel for conveying material through the helical channel along the at least one helical flight, the advancing grooves being parallel to and having the same first helix angle as the helical flight; characterized in that the longitudinal portion further has a plurality of noncontinuous cross-cut grooves (37C, 37N) oriented in the first threaded direction common to that of the helical flight and/or in a neutral direction parallel to the longitudinal axis and traversing several of the plurality of advancing grooves; and at least one of: (a) at least one of the plurality of advancing grooves having an advancing groove depth taper including an increasing depth taper or a decreasing depth taper; and (b) at least one of the plurality of cross-cut grooves (37C, 37N) having a cross-cut groove depth taper. (a) at least one of the plurality of advancing grooves having an advancing groove depth taper including an increasing depth taper or a decreasing depth taper; and (b) at least one of the plurality of cross-cut grooves (37C, 37N) having a cross-cut groove depth taper.