Effects of Temperature on Ammo

[LongRange]

If you're worried about temperature variations in your loads, simply switch powders.

The ballistics group at IMR has tested this powder from -40 to +165 degrees Fahrenheit with virtually no performance variation.

http://www.imrpowder.com/8208xbr.html

you do know that ALL of their testing is done indoors where most environmental's other than temp dont change right?

to the OP...ive shot(300WM)in the most extreme environmental's you can think of...now im on the west coast so maybe not as cold as you guys get but close enough. ive shot in light to pouring rain,light to heavy snow,9degs to 105degs.0 to 35mph winds and everything in between because like you i wondered the same thing and what i can tell you from all of that is that you need to go out and shoot in these conditions to know what changes weather has on point of impact. in my 300 70.5g of RL-22 in nosler brass with a CCI250 primer and a 208g hornady is good from about 70degs and up with slight elvevation changes regardless of conditions and 71g RL-22 in the same brass with the same primer is good from 9degs to about 60degs regardless of conditions. with that said i will tell you that rain and snow has a HUGH effect on POI...i shot one day in a light snow with the 71g load and had 6 hits out of 10 fired at 1010yds on 6" AR500 plate targets...the next day from the same place with the same load but heaver snow falling i could not hit the 6" targets but shot a 10" group on an 18" target.
an easy way to access temp changes on ammo is to go out on a hot day and pak a lunch box full of ice,put 5 rounds on ice,5 rounds in the shade and 5 rounds in the sun and shoot each group from a cool barrel....keep in mind ALL powders are temp sensitive(just some more than others) I dont care what ANYONE says its a fact!!

[yobuck]

you do know that ALL of their testing is done indoors where most environmental's other than temp dont change right?

to the OP...ive shot(300WM)in the most extreme environmental's you can think of...now im on the west coast so maybe not as cold as you guys get but close enough. ive shot in light to pouring rain,light to heavy snow,9degs to 105degs.0 to 35mph winds and everything in between because like you i wondered the same thing and what i can tell you from all of that is that you need to go out and shoot in these conditions to know what changes weather has on point of impact. in my 300 70.5g of RL-22 in nosler brass with a CCI250 primer and a 208g hornady is good from about 70degs and up with slight elvevation changes regardless of conditions and 71g RL-22 in the same brass with the same primer is good from 9degs to about 60degs regardless of conditions. with that said i will tell you that rain and snow has a HUGH effect on POI...i shot one day in a light snow with the 71g load and had 6 hits out of 10 fired at 1010yds on 6" AR500 plate targets...the next day from the same place with the same load but heaver snow falling i could not hit the 6" targets but shot a 10" group on an 18" target.
an easy way to access temp changes on ammo is to go out on a hot day and pak a lunch box full of ice,put 5 rounds on ice,5 rounds in the shade and 5 rounds in the sun and shoot each group from a cool barrel....keep in mind ALL powders are temp sensitive(just some more than others) I dont care what ANYONE says its a fact!!

See, your gettin some really good advice and your just not listenin. lol
Could it have something to do with not comin in out of the rain also?
How can you ever expect to make first round cold hore shots if your using the wrong powder?

[LongRange]

See, your gettin some really good advice and your just not listenin. lol
Could it have something to do with not comin in out of the rain also?
How can you ever expect to make first round cold hore shots if your using the wrong powder?

im not sure what your trying to say here but i do make first round cold bore shots more often then not....