04-01-2012, 11:37 PM
Grimmy Wrote:I have ran reloader 7 in my 300aac and it is very quiet. Don't know what that would be in the Grendel as far as case load density but it is really quiet. My load was 10.3 grains. Like stated start high and reduce!!! Also remember what is quiet on a cool day may go trans sonic on a warm to hot day. My target velocity is between 1000fps to 1025fps max. Up here in Pa we have a large temp swing and I want a loading that works in any temp I encounter. L had loads go super sonic just from setting in the chamber and absorbing heat from previous fired rounds.
If your loads are breaking over on a hot day it's probably due to the powder burning faster, not the atmospheric conditions the bullet is traveling through. Here's a link that helped me to understand more on the speed of sound. It also has a speed of sound calculator.
http://www.sengpielaudio.com/calculator-speedsound.htm
The higher the temperature is, the higher the speed of sound threshold is. As I understand it, an object can travel faster on hot day and not create a sonic boom than it can on a cold day. You might consider trying a powder that's less sensitive to temperature swings.