Ok, I'm still trying to decide which powder to begin loading for my .223. Many recommend Varget, Benchmark etc. but others talk about "extreme or temperature sensitive" powders. If you were to choose one powder for all your varmint hunting from groundhods to coyote, what would it be? What is an example of a powder that is not temperature sensitive? Thanks for the help.

Most of the new Hodgden powders are not temperature sensitive. Varget is one of them. It means the load you work up in the hot summer will still shoot almost the same when it is below zero. With the older powders, if you worked a hot load in cold weather, pressure could get dangerous in the summer. Velocity variations would change day to day depending on the weather. Be thankful for the "extreme powders".

The good news is that in some cases, the "extreme" powders work very well. 46 grains of Varget in my 308, with a 165 grain bullet, gives me a "zero temperature coefficient" load. I've tested it in hot weather, and in cold, and the MV is very close to identical.

The bad news is that it often doesn't work that way. In my 223 Rem, Varget produces a load that is more temperature sensitive than the Winchester "white box" commercial/military ammo.

In my instrumented 7.62x54R Finn, which is close to the same case size as the 30-06, my Varget load rises 203 PSI for each degree F the barrel temperature rises. A 95 degree F barrel produces pressures about 6,100 PSI higher than the same load when the barrel is at 65 F. That's conspicuously NOT temperature insensitive. Nor is it insensitive to the temperature of the powder.

There is some other variable in the mix, such as case capacity, or percent case fill. If you get the right combination, it works great. But do not depend on "extreme" powders always being temperature insensitive.

Hmm, and I thought it was made exclusivley for snowboarders and skydivers.