CCI quiet fires at 64DB from a rifle. For you guys that remember eletric type writers. Stand 10 feet away while someone is typeing , thats 64db. That is fairly well quiet round. Cb is slghtly less but with very light bullet. You can shoot and hear the fireing pin click in a bolt rifle. The Quiet will not cycle in a semi-auto unless it has a very well use recoil spring and is over all and very slick bolt and reciever. I have 2 -10/22's, Wifes is a 1973 ruger with a stock recoil spring and polished where it wears and rides. My rifle has a Kidd light recoil spring in a fulliy polished bolt and reciever and will not fully cycle them. Maybe one out of 6 will cycle. My son-in-laws new marlin 795 will barely open the bolt. Guess to have a semi-auto work with them it had better be well along in years and shot alot. Get a bolt rifle to work 100%.
The round makes a practical yard cartidge for varments or close work, 25yard hunting cartidge. Even makes a good plinker for young and old kids. It will not travel down range like a run of the mill 1200fps round.