What is the best ammunition to cycle and make a 9mm as quiet as possible with a suppressor? I have some winchester 147gr fmj subsonic with my Walther PPXSD it's not really loud and using the sound meter on my phone it's staying around 73-80dB which is the terrible at all. Also that using a Silencerco Osprey 45 suppressor will be picking up a couple of my 9mm suppressors this coming weekend. Thanks.
Frankly I'm working on quieting the slide and mechanical noises to reduce the overall sound at this stage. 73-80db is very quiet for a firearm discharging. Many of the marketing materials suggest expecting around 100db with a suppressor.
Let me suggest that the 73-80dB range being displayed on your phone is so ridiculous that you should consider the device worthless for measuring the sound of your firearm discharging. Not possible. Anyway, 80dB is twice as loud as 70dB, so your range of sound (if it were real), is very broad indeed. Here is a chart of fans ranging up to 72.6 dB. Is your gun as quiet as an electric fan???? http://www.tomshardware.com/reviews/a-comparison-34-coolers-amd-athlon-xp,576-40.html Here is a world record cat purring at 73dB. http://www.stuff.co.nz/life-style/cutestuff/4831143/Smokey-the-worlds-loudest-cat-purrs-at-73dB Normal conversation is 60-70dB (might be more depending on who is in the room!). 125 dB is about as quiet as you can get a 9mm, and that requires a quality gun muffler.
Like MP said, definitely not an accurate reading. A firing pin striking the primer is between 115-120 dB alone.