"M" is the ejector.  It hinges in the floor of the bolt opening of the receiver, where it lies flat.
  A lobe on the tail of the ejector is acted upon by the Bolt as it is drawn back.  At the end of bolt travel, the ejector rises.
  The tip of the ejector makes contact with the fired cartridge case, which is held against the Bolt face by the extractor.  The fired case flips out of the action when its base contacts the ejector.

Part "S" is a flat spring that powers the follower arm and puts spring pressure on the Magazine gate.

(Here's a more complete schematic from the KCA Photos page).

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