Are the corks doing this over time? What are your temperature fluctuations on storage. It also looks like one bottle has some gas left in the wine aswell? Did you leave the bottles upright for a week to allow the cork to seat correctly and form the neck before putting them on their side?Anyone ever had this problem?
Is it defective corks, this happen 4 times in a roll.
See attached photo.
I've only probably bottled about 1,500 bottles that I can recall with my floor corker, however there are alot of recycled bottles in there and I haven't had any issues with the corks. I also cork screw top bottles aswell. However, I don't bottle gassy wine, I ensure temps between summer and winter are not drastic and I seat the bottles upright for a week before cellering on their side.