Freezing, as in left in freezing temperatures for a winter's storage?
About all I can say about temperatures and loaded ammo is if you work up a max load at, say, 70 degrees ambient during your shooting/testing, they'll shoot a bit lower in cold-weather hunting, and maybe flatten primers on a hot summer day. Generally, unless you're pushing the envelope the latter is not really a problem. The first case might cause a low shot on that 6x6 elk.
I have read--and believe--that storage of your ammo or reloading powder in 90 to 100 degree temperatures for a long time is detrimental; the chemical decay reduces the power. But cold? I don't know, but I don't think it would hurt, from a chemical decay standpoint.
I'll defer to anybody who's more up on it...