Wim---once you cock and lower the hammer to half cock, you have already advanced the cylinder (with a round in the chamber) and this is the noisey part. Now to go from half cock silently, all you need to do is pull the hammer back to full cock while holding the trigger rearward, release the trigger while still holding hammer in rearward position and you are again at full cock and ready to fire. This sounds harder to do than it really is. Practice this with all chambers empty. As long as you don't slip off the trigger or hammer, you are fine. When you do this with live rounds, be sure and point in a safe direction, just in case! Gene