Originally Posted by WinterWizard
OP, sounds like an extractor issue to me, if your extractor is failing to grasp the rim of the casing and pull it out of the chamber.
Inspect your extractor closely, even perhaps remove it from the slide and thoroughly clean it. Often times, that slide has been released on an empty chamber many times in the gun store by stupid idiots and that extractor can be chipped or otherwise damaged, which is why I prefer to buy brand new guns that haven't been pawed up by the idiot masses.
Dropping the slide on an empty chamber should have no affect on the extractor, possibly dropping the slide on a round that you have manually dropped. Into the chamber after a period of time MAY have an affect but I still question that,being hardened as it is and moving over a brass rim and being spring loaded.