If you put a suppressor on a 10/22 and shoot Aguila SSS Sniper Subsonic Ammunition 22 Long Rifle 60 Grain Lead Round Nose.....with fast twist barrel..
It is not going to be quiet.
The over all length of the ammo is 22 long rifle, but the case length is 22 short.
The bolt will move back, extract and expose the case mouth to open air when the chamber pressure is still above 2 atmospheres.
This allows the escape of super sonic gas from the breech which will be loud.
In a similar situation, 2 stroke motorcycles sometimes cannot pass noise regulations with mufflers, because noise is coming out the air intake of the carburetor.
