Reloading for variouse temps.

[kirbymagnum]

I have found a good load using Varget powder however this load was developed with temperatures around 75F and now the temps are between -10F to -20F. How much more powder should I add to make up for the decrease in temperature/pressure?

[WrzWaldo]

Varget is a Hodgdon Extreme powder and as stated on the Hodgdon site...

TEMPERATURE EXTREMES

You live in the "real" world, where 12 point bucks are rare and it’s never 70° when you decide to fire your rifle. Where you shoot it’s either freezing cold or burning hot. Not exactly ideal conditions for your rifle, or you for that matter. Fortunately, Hodgdon’s Extreme powders perform just as well at 125° as they do at 0° . Using an exclusive extrusion process and exacting quality standards, Hodgdon has created a line of propellants that performs better at hot and cold temperatures than any other powder on the market. So when you sight in your rifle this summer, you can count on unbeatable accuracy this winter.

I've never shot any at or below freezing, but from about 40 to 90 degrees F I have found it to be pretty consistent. I would just workup new loads for those extreme low temperatures.

[Bubba]

Personally, I wouldn't worry about it.

JMO
Bub

[crashcarruthers]

I would shoot a few rounds to check my scope and make sure my point of impact hasn't changed. If it hasn't then there is no good reason to change the powder charge. Good Luck and be Safe!

[kirbymagnum]

Thanks for the help. I'm going to shoot a group and then I will be able to tell if I have to work up a new load.

[WrzWaldo]

Here are some exterior ballistics to chew on as well.

[kirbymagnum]

There is a fair bit of velocity difference due to the air being more dense in colder temperatures. I will post my groups from when I shot it in 75F and after I shoot from this weekend and then we will be able to see how much the temperature affects the Varget powder, if I can do my part.