Cold Powder

[Jayhawker]

Got a brand new .308 and a bunch of loads made-up with Varget, 4064,W748 and IMR 4895 to test 100 meter accuracy. I can handle the 35-40 degree weather but will the temperature affect the powder and invalidate my accuracy results once the weather warms up to a temperature that I do most of my shooting?
Pete

 

[GRIZ22]

I don't think so unless you are loading max loads for your gun (not the same as max loaded in the manual). I have worked up loads in cooler weather and checked them when it got warm and found no big difference. Maybe 50-60 fps in a 30-06 and no difference in accuracy.

I have a 270 that shoots well but the barrel might be tighter than normal as high pressure signs start to show below what the manuals say is max. I worked up my loads for this rifle in hot weather and have no problem.

 

[USSR]

...will the temperature affect the powder and invalidate my accuracy results once the weather warms up to a temperature that I do most of my shooting?

Significant change in temp will effect all powders, although the Varget to a much less degree than the others. Obviously, the effect will be a drop in velocity in cold weather, and a rise in velocity in hot weather. Whether or not the change in velocity effects the accuracy of the load is only something that can be determined thru testing.

Don

 

[Pumpkinheaver]

The hodgden "extreme" line of powders is supposed to less prone to velocity changes due to temp.

 

[30Cal]

W748 is the only one I'd worry about. Ball powders are far more sensitive than extruded.

Ty

 

[mc223]

The Hodgdon website has data exactly like you are looking for.

found the link: http://www.hodgdon.com/smokeless/extreme/page3.php#308win

 

[DWARREN123]

I would worru that a max cool weather round would become over max in hot weather. Accuracy may or may not change, you just have to see.