I have recently fired the Aguila Super Colibri 22 ammo which has no powder and only a primer charge propels the bullet. I also fired the CCI 22 short CB cap which had about the same reputation as the Aguila ammo. Both were fired though a Beretta 21A. The rumor was that the drop of the hammer was louder than the report of the bullet(s). Nothing could be further from the truth. If people said that the "crack" of the bullet is signifigantly lower I would have believed it, but to say that these bullets are quiet is a gross mis-statement. They were quite loud and much louder than a BB gun, ( which I also read on some forums) and I in no way could hear the drop of the hammer. Even a pseudo surpressor had next to no effect on the sound. I can only say that the bullets can probably be fired by most people outside w/o the need for hearing protection. But, quiet.... certainly not!