Calculating the speed of sound


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Lennyjoe
May 4, 2014, 04:38 PM
All, Looking for a good online tool to calculate the speed of sound based off of elevation and temp. Anyone have any good links?

I took the Blackout for a test run today and am extremely happy with the results. I'm cutting down my own LC 5.56 brass, using AA 1680, 208 gr Hornady HPBT bullets. As for the rifle, its a 16" DPMS 1-7 twist, carbine gas system, AAC Cyclone suppressor, Primary Arms red dot sight and Sightmark 3x magnifier.

The photos are of the rounds down range at 25 yards to check cycling and speed. It was 85 degrees out and our elevation was 4400 ft. 11.7 gr of AA1680 went through the chrono at 1170fps. And when I got down to 10.8 gr the bolt wouldn't cycle back all of the way. Shot 11.7gr, 11.4 gr, 11.1 gr 10.8 gr.

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Lennyjoe
May 4, 2014, 04:44 PM
By using this site: http://www.digitaldutch.com/atmoscalc/ as well as air temperature of 85 degrees Fahrenheit and elevation of 4400 ft, it showed the speed of sound at 1188 fps.

moxie
May 4, 2014, 04:45 PM
See here:

http://www.sengpielaudio.com/calculator-speedsound.htm

http://www.srh.noaa.gov/epz/?n=wxcalc_speedofsound

jerkface11
May 4, 2014, 07:24 PM
I use an ap called ballistic. Just tell it the temperature and air pressure and it will tell you the speed of sound and your drop at whatever range.

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