Thread: Suppressor sound testing

Originally Posted by Friwi

To sneeze: when I stand in the but for marking targets at my local range, I prefer to ear the gentle bark of a 223 or 6 mmbr bullet than the one of a fast 30 cal or 338!
So the size of the projectile and its moving speed has definitely an influence on the noise it produces when moving through the air.
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The noise level is largely proportional to the amount of powder burned, not what's coming out the barrel. A good comparison is a .223 v .22-250. That's why I got rid of the latter.

Originally Posted by Friwi

To sneeze: when I stand in the but for marking targets at my local range, I prefer to ear the gentle bark of a 223 or 6 mmbr bullet than the one of a fast 30 cal or 338!
So the size of the projectile and its moving speed has definitely an influence on the noise it produces when moving through the air.
.

Yes it it does, in this case DPT is using a 150gr from a 308. It would be interesting to know how much of the sound is from bullet vs powder for this particular test. That would in turn show us how much sound is able to be suppressed ( noise form powder burn from a 308 shooting a 150gr) and in turn what percentage of that the suppressor is achieving.

A bit of a belated thank you to Bert at ODL for his time and use of his testing gear, and his advice and experience on the use of liquid medium in sound suppression.

Darren
Does a reduced load i.e. Trailboss bring the sound down? We just use an extra baffle currently on the 223. Very quiet.

I summarised this from an article on supressors which I found interesting. Someone will no doubt put me right if bits are wrong. It certainly helped me understand how they work.
Approximately half the energy developed by the propellent when a cartridge is fired goes to make the bullet go forward the rest is shared between recoil, gas pressure energy, gas thermal energy and gas kinetic energy.
At exit, gas pressure in the barrel is around 10_15,000 psi with a temperature of about 1000 degrees c and its travelling at supersonic speed.
The energy in the gas is divided up roughly as heat 96% pressure 3.5% and kinetic the balance so getting rid of heat and pressure are key.
As the volume doubles the pressure halves so big volume in a supressor is good, also as the temperature halves the pressure drops a corresponding amount. Baffles increase the surface area cooling the gas more quickly and also kill off kinetic energy by creating turbulence.
The ultimate aim is to have bought the propellent gas speed down below the sound barrier and to have reduced the volume as much as possible by cooling so it escapes to atmosphere quietly leaving the sonic boom of the bullets flight as the only sound

Originally Posted by R93

Robbie Tiffen told me years ago that you could reduce the decibels by spraying CRC inside a suppressor but I never tried it.

Interesting. I wonder what effect if any it would have on accuracy.

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grabbed one these today to throw in the range bag . . . certainly small enough to carry up the hill if it works . . cheers for the idea