The quiets aren't good on small game. I had to shoot a rabbit 3 times in the head before it stopped flipping and flopping around.
The cci subsonic segmented HP on the other hand are just as silent as the quiets but devastating. Rabbit headshot with one of those anchored it without a twitch, and left its eyes about popped out of their sockets.
Are those the same as the CCI CB longs that sound like a pellet gun going off? If so, I've killed a truckload of squirrels, rabbits, groundhogs, and coons with them over the years. We used to call them "posted land shells " when I was a teenager.
I also shoot squirrels and chipmunks from the backdoor with the Colibri. I've made 35 yard head shots on chipmunks and it's click/flop. 420 fps on the box(for pistols only). I chrono'd it out of my 24" bolt action at 290 fps. It's miniature artillery. I watch the bullet drop in on them. I do keep a cleaning rod on the mantle for the rare one the doesn't exit the bore. Quite & fun.