While I don't use dental floss, I use core strands from paracord, I just insert the cord int the spring, back it out a blonde one, cut, and make sure it sits in fully. I do get an occasional one that the cap doesn't want to seat right, but I get that with and without the mod.
On F's my opinion is the vast majority of the rings and rings comes from the springs ratting from the vibrations of every keystroke. So with the floss, it dampens the vibration just enough, lime putting your finger on a pluked guitar string, but not pressing down to the board/fret.