JDP12 wrote:Think I beat JSR to this one..
So you did
at work so I can't really watch it with sound on.
It's interesting to compare dB levels, but what your brain actually interprets from the ears' input is remarkably subjective.
Here's a list of airguns tested for dB levels:
http://www.straightshooters.com/decibel ... rguns.html
The above also includes the readings of some common "household" noises to give a sense of perspective.
Here's a list of commercial firearm silencers:
http://silencertalk.com/results.htm
Many manufacturers will tell you "as quiet as a pellet gun", the dB data (measured on different days with different instruments in different places, so it cannot be compared so exactly) suggests otherwise, with the quietest 22LR silencer at around 120dB while the quietest airguns are around the 90dB mark. Remember that dB is a logarithmic scale, here's a list from howstuffworks showing how the numbers pan out:
Near total silence - 0 dB
A whisper - 15 dB
Normal conversation - 60 dB
A lawnmower - 90 dB
A car horn - 110 dB
A rock concert or a jet engine - 120 dB
A gunshot or firecracker - 140 dB
Interestingly, I managed to find a dB rating for one of the Russian "captive piston" rounds in this article:
http://sadefensejournal.com/wp/?p=307
In order, the individual shots of the 5-round string were measured at: 125.0, 124.5, 124.5, 123.8, and 125.0 dB. The overall average was 124.6 dB
This for a muzzle velocity of 620 fps, and muzzle energy of 133 ft/lbs - much slower than a subsonic 22LR, and only a little more muzzle energy. The projectile however is steel, and with almost double the frontal area, so it would cause significantly more tissue damage - and of course, the PSS that fires the cartridge is much more compact than even the smallest 22LR pistol and suppressor combination.
Interesting how it still makes so much noise in spite of the fact that no gas escapes the cartridge. Must be a combination of piston slamming into the case, action noise and this effect:
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=AD0334799