A flow-through discharge assembly having a rotatable tube section and an opening through which product is discharged and a positioning apparatus for rotating the tube section between operation and non-operational conditions. When the tube is positioned in an operational orientation, grain exits through the opening for discharge from the assembly. When the tube is returned to a non-operational condition, the tube opening is blocked and grain is prevented from exiting through the opening. The tube opening may be a single elongated opening or may include multiple tube openings through which product is discharged. A method of using a rotary discharge assembly to control grain flow within a grain handling system is also disclosed.