Final answer:
The transport tray or case conveyor is the subassembly in a replenisher that moves spent cases and unfired rounds from the loader to the downloading gates.
Step-by-step explanation:
The subassembly of the replenisher that supports and transports spent cases and unfired rounds from the loader to the separate downloading gates is known as the transport tray or case conveyor. This component is critical in the proper functioning of an automatic or semi-automatic weapon's loading and reloading mechanism. It ensures that both the spent cases and the unfired rounds are moved efficiently, minimizing the risk of jams and ensuring a smooth operation during rapid firing conditions.