Originally Posted by MacCool

Interesting thread at M4Carbine on ejection/extraction issues on the Gen 4 and later Gen 3 Glocks. To be sure, a lot of it is classic Internet mental masturbation, but erratic ejection really is a hallmark of the later Glocks. I have both a G17 and a G19 and both will put a casing on the bill of my hat with fair regularity.

Skimming through this thread will shed some light. Don't try to read it all.

Glock Extractor Issues Gen 4 - Gen 3 - M4Carbine.net Forums