Home Forums Hunting & Shooting Ask The Gunwriters Do different powders create differen noise levels?

When I took Acoustics in electrical engineering, the professor was Rubens Sigelman, ultrasound pioneer. The book was Kinsler
https://www.amazon.com/Fundamentals-Acoustics-Lawrence-Kinsler/dp/0471029335

I should have been able to figure this out:
Why does a 22 with 22" barrel sound like a loud gun, but a 22 with 24" barrel shooting rem CB longs sound like a BB gun? What is going on with 2 more inches of barrel?

I could not figure it out.

I asked proffesors. I asked everyone.
The late experimenter and gunsmith Randy Ketchum, said, "That is the threshold of supersonic gas escapement."
I knew he was right.
The gas ball at the muzzle would be noiseless until it slowed down to the speed of sound and then propagate a wave with harmonics rolling off at wavelengths below the gas ball size.. That is why cannons have a deep boom, like woofer speaker. 1000 Hz is a wavelength of 2.5 feet. A gas ball 2.5 feet wide would be attenuated at sounds lower than 1kHz, but still audible as low frequency carries further and around corners.

The next question I sought help on was "What is that threshold pressure?
The answer was from a guy whose on line image was a biker in CA with tattoos, strippers, and was a recording engineer. He calculated one atmosphere above ambient.
I knew that would be a natural threshold as a peak wave of 2A would have a trough of a 0A, which is the threshold of cavitation. Sound will not go lower than that.
So I knew he was right.

I started seeing the muzzle pressure in Quickload as being as high as 10 kpsi.
The problem with that is the chamber plus barrel volume will also affect the size of gas ball.

I began experimenting with what would kill big game, sound like a BB gun, and not have a suppressor.


This is several old 12 ga shotgun barrels with remchoke male threads on the breech and remchoke female threads on the muzzle.
The correct answer was not this. That is quiet, but awkward.


The correct answer was a 50 caliber rifle wildcat made from 56-50 brass with an extremely high expansion ratio.