[tomzz]

One poster above said about like a 45 ACP. I was guessing just based on air rifles I've shot in the past.

[Chode]

i am basing it on my old paintball guns that are .62cal but maxout about 400fps

there is still no supersonic crack at 700+fps... that's around 1000+fps give or take depending on elevation and air density

it prolly sounds more like a 40mm blooper/thump gun than anything. i doubt it's anywhere near 120db

but that's just my SWAG.