Your extractor tension needs to be correct too - if it's too loose it could conceivably cause the problem you're describing. Here's how to check for proper tension. The video is for a 1911, but the principle holds for pretty much any semi auto pistol.
Something else that's worth noting - you will usually see a round impression on the face of the block that's created when you fire rounds. That circle will pretty much be right in line with the barrel WHEN IT'S IN BATTERY. This is NOT where the round is when it extracts. As the slide moves back, the barrel dips down and the cartridge head slides down the face of the block until it is contacted by the ejector and kicked out of the action. Consequently you want to look closely at the bottom of the extractor claw. There should be an angle on the lower inside edge, but the amount of missing material should be minimal. If the 'piece of the corner' that's missing is too big it could slip off the round before it ejects.