The Accurate Reloading Forums
Temperature and velocity

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22 February 2003, 11:22
BossMoss
Temperature and velocity
I was at the range to day testing loads it's around 35deg. I was getting around 3700 FPS out of my 22-250 with 36gr of reloader 15 & 50gr bullett no pressure signs yet & good accuracy. Will I get a increase in pressure and velocity when it gets warmer? Are their any reports on what I might expect?
22 February 2003, 15:06
mete
Yes you will get increase in both pressure and velocity. For 30-06 a load which is 42,000psi at 70F will rise to about 49,000 ar 120F. Velocity goes from about 2680 to 2740 fps. ( from Norma data) If you start out at higher pressures the change is more dramatic. Develop max loads only in hot weather and when using them keep ammo out of direct sunlight.
22 February 2003, 15:18
Bob338
As for expectations, tou'll get an increase but it will vary with loads, propellants and temperatures. I've tried to make some semblance of sense out of what occurs using both a temperature gauge and hygrometer, along with chronograph. Bottom line is all propellants react differently depending on just about everything imaginable.

I will say I think you will be OK with your load even with a 30� increase in temp. Just be wary of any external pressure signs as the temperature increases.
22 February 2003, 15:45
ricciardelli
http://stevespages.com/tempvsvelocity.html
25 February 2003, 03:25
Dutch
There is some interesting info about temp and velocity at the Hodgdon site. Take the "extreme tour". HTH, Dutch.