Complex sentence: The primary feature of the De Lisle was its extremely effective suppressor, which made it very quiet in action-indeed working the bolt to chamber the next round makes a louder noise than firing a round.
Split into simpler sentences: The primary feature of the De Lisle was its extremely effective suppressor, which made it very quiet in action. So quiet, in fact, that working the bolt to chamber the next round makes a louder noise than firing a round.