Gator I have shot tens of thousands of rounds of colibri from my break action 22 rifles. Out of a pistol I agree, but a 20" barrel it does, in fact, sound like an airgun. Great thing is that you can get it shipped to your house from midway for about $25 per brick.
My .22 Sheridan 392 is actually louder than this ammo, and so are my springers by a factor of 2. I does however sound EXACTLY like my co2 benjamin. Out of my 28" CZ Silouette gun you can hear the firing pin crunch the rim.
Pistol is loud, but out of a rifle it is great stuff. many a squirrel have fallen to it.