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Extractor = pulls empty shell from the firing chamber.
Ejector = hits pulled shell on left side/back of rim to throw it out the port.
Port = shell should clear without contacting any edge of port.
Timing = controls all of the above.
Recoil Spring = partially controls timing.
Firing Pin Stop = also partially controls timing.
Hammer Spring = also partially controls timing.

Have a look at the EJECTOR like the post above yours suggested.

Extractor clocking can also cause erratic ejection of the shells. If clocks on extraction I suppose it could have an erratic hook on the shell when it hits the extractor. But it is more noticeable as a fail to feed problem.