Most of the ones I see with problems, are failure to extract, usually accompanied by a part of the rim being ripped off, by the extractor. 9 times out of ten, the gas ports are clogged, just like model 1100 and 1187 shotguns. The owners clean the bore and chamber alright, just don't know to keep the ports clean. I keep a gross of pipe cleaners around for cleaning them, sometimes have use drills to get the carbon out. When the ports are dirty, it tries to extract the round before the pressure in the case has bled down, and the brass is still firmly attached to the chamber. Bad reloading practices make up for a lot more FTF and FTE.