Those are good, I have also had good luck with CCI .22 CB Longs. I shoot them in the house and the just about the only thing you hear is the clang when it hits the steel target.
edited to add, same power (or lack of it) as the CB caps. However, they reliability function in bolt, slide, and lever action rifles designed for .22 LR. Good for semi-autos as well if you don't mind cycling the action each time.
The Aguila Super Colibri is fairly quiet, though I'm not sure how the slug itself performs.
I use the Aquila rounds. Those Super Colibri rounds sound like a pellet gun. Fairly accurate too. My BIL has killed a hundred squirrels with that bullet.
Would only recommend for revolver use.
22 cb caps
I had the same issue with my pellet gun being too loud... I gave it away and use the 22 now.I went to the Waco Gander Mountain grand opening the other day. Bought some boxes of CCI Quiet-22 40 grain 710 fps lead round nose. They have it priced at $3.99 for a box of 50 right now. I have a little bit of trouble cycling it in my Winchester semi auto rifle. But I think it's the quietest 22 LR I have ever used. It's honestly not as loud as one of the 177 pellet guns I shoot. I will be using this stuff on squirrels.
The SSS rounds work pretty well in a 10/22. One of their selling points is they cycle in semi autos.I had the same issue with my pellet gun being too loud... I gave it away and use the 22 now.
Has anyone used the Aquila 60gr sniper subsonic? I bought a box but haven't used any yet. I bought them in case I need to be quiet but still hit harder than the kolibri does