They need at least standard velocity to function, as there is no powder in the Quiets, and not enough recoil to move the bolt.
I've seen this statement here on CGN a few times and in other forums. Do you guys not own any pliers? Just pulled one apart, and this was inside:
I guess not technically a 'powder' exactly, but having pulled apart 12ga, 9mm, and .22lr from a few companies, these little rough discs look kind of like most other powders. More silvery? But definitely not just the primer firing. To be fair I have pulled one apart some years ago to check what was inside and saw only a dozen or so flakes, so maybe they're just really inconsistent in the powder loading. I do get the odd '710fps' CCI Quiet shooting a bit louder than the rest, so that would explain it.
As for CCI Semi-Auto Quiet cycling a 10/22 I'd guess that has as much to do with how well broken in it is, besides any tweaks to make it cycle more smoothly. In my nearly-new 10/22, nope, not even close. Jams and fails to eject pretty well every time. And that's with the bolt and the ways polished, the bottom-rear ground into a radius and brought to a mirror polish, face of the hammer polished, every rubbing part polished, bolt release mod, fuel line over 1/8" steel rod buffer, and just a trace of light oil on the bolt to keep it from galling the aluminum of the receiver. CCI SV cycles 100% reliably. And the rifle likes that, so that's what it'll be shooting. I'll save my semi-auto Quiet for bolt rifles. I suppose I could start drilling out the bolt to lighten it and swap for a softer spring, to make it into a CCI Quiet only, or Semi-Auto Quiet only rifle. But that seems a bit limiting to me.