Quote:
Originally Posted by Rikky Lee
But in what ambient temperature? The colder it gets to 32 F or zero centigrade the closer the speed of sound is to 1080fps.
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At 0C the speed of sound in dry air is 1087.3 ft/sec. There is very close to a 2 ft/sec change in the speed of sound for each 1 degree C change in temperature. That simple rule works over the temperature range humans can tolerate. In my opinion for low bullet noise and optimum subsonic bullet stability muzzle velocity should be between 100 and 150 fps slower than the speed of sound. That does depend some on bullet shape but not a lot. I live in Arizona at a mile elevation and load for 1000 fps for 300 Whisper and heavier subsonics . Here there is low air low air density and temperatures from -20C to +40C. Speed of sound from 1040 to 1170 fps.