How loud is it with a suppressor?…
Like the answer to so many things, "It depends."
There are military standards for testing that test the sound pressure 1 meter lateral to the muzzle. This is not a great measure to evaluate the potential for hearing damage to the shooter, so some companies report "at the shooter's ear."
Then, of course, the sound pressure is going to vary with atmospheric pressure that, in turn, depends on altitude, humidity, temperature, and local barometric station pressure.
Finally, what ammo is tested? Supersonic? Subsonic? Manufacturer (different powder burn rates), barrel length, brand/model of suppressor, etc.?
Think about "hearing safe":
https://www.noisehelp.com/noise-dose.htmlA typical .22LR rimfire
pistol shooting "subsonic" (the speed of sound varies with atmospheric pressure) ammunition with just about any decent brand of suppressor will be <124db. A rimfire
rifle, suppressed, using "subsonic" ammo, typically <120dB.
Subjectively, to my ears, about the same as an air rifle unsuppressed. My caveat: I wear hearing protection (muffs and plugs) unless I am confident I am receiving <124dB at my ears.
Here's one manufacturer's test data (they manufacture the Sparrow):
https://www.silencershop.com/blog/post/22-suppressor-test-results It is typical (and annoying) that they didn't describe their testing methodology and atmospherics at the time of testing.
I have attached one of the original .300BLK papers that, though the testing procedures are not described, but presumed to be the military standard, includes some sound
centerfire pressure comparisons on page 25.