trailer,

Depending on the powder being used and the outside temperature, There could be no difference to a great deal of difference. Some powders seem to lend themselves to radical differences. It hasn't been very long ago that you worked up your loads in the summer, and rezeroed your rifle for the cold weather. The one make of powder I've had the graetest experience with was Dupont/IMR. I lived in Alaska for awhile and learned the hard way. My first summer there I worked up different loads for my '06 using IMR 4320 for the light bullets, up to 150 grain, and IMR-4350 for the bullets 180 grains and heavier. Well everything went just fine until we went after caribou between Christmas and New Year. I had a chance at two great bulls at less than 100 yards. I seem to recall firing about ten rounds and never touched a hair. When I checked the rifle I found it was off over six feet. I rezeroed the rifle and got two bulls the next day. I also found the cold weather velocities of my rifle were 150 fps slower than warm weather velocities.

When Hodgdon brought out their Extreme Powders I did a little testing with Varget. The test ran for three winters and two summers. On the coldest and hotest days we have in New Mexico I'd go out and shoot the loads for my daughters 7mm-08. I would shoot a string of ten shots over a chonograph and use the average of those shots. Well the temperatures didn't go to fifty below, they did run from over a hundred to the low teens. The test also used three different lots of powder. The extreme spread of velocities was slightly over 19 fps, with no change of zero. As a result of the test I made I now use Hodgdon extruded powders for all my rifle reloading. I no longer have to worry about change of zero or velocity change.

This subject comes up every once in awhile, and I've read entries where others have stated their powders are insensitive to temperature changes. If you do a little research of the site you should be able to come up with additional information. I started to test two other powder and dropped them pretty quick when they didn't give me the initial accuracy I wanted or reacted to temperature changes. The Hodgdon Extreme powder is the only powder that I am comfortable recommending as being insensitive to temperature changes. I hope that this is of some help.

Good luck and God bless.
Bob