Besides that it's uncomfortable.
Let's arbitrarily define cold as +10 and extreme cold as -10 and below. There's at least 2 variables in play here, powder and lube performance. There could well be other factors.
It's often said that some powders don't ignite well or perform variably in cold... 296 comes to mind. Thoughts?
Lubes?? Anyone test or have experience accuracy-wise in real cold? What are we looking for in terms of qualities and the ingredients that make it work?
I have hunted in cold for many years and shot some bucks down around zero. Never with cast, though. Also I have never conducted load development or shot groups much below 20 degrees.
Seems like studying this might lead to better understanding of how powders and lubes work in general.
+10 to -10 is pretty balmy, at least by our historical standards. Tho, the past few winters have seen the majority of our temps in that range, with periods of -20 to -40 or colder being short and infrequent. Currently it's only -8 here at my cabin (I just strolled outside with a headlamp in my birthday suit so I could accurately report that) and is predicted to warm up to about +10 again tomorrow. Apparently, record warm winters are becoming our "new normal". (It used to be that we would never say "negative" when speaking of the temperature, because during winter it was typically always in the negative range, so it went without saying. But for at least the past 4 years that doesn't hold true anymore, and our winters are continuing to get warmer).
I commonly target shoot the .45 Colt in that +10 to -10 range but don't have any hard data to offer. LCD screens and plastic parts don't like negative temps, and in winter I have to snowshoe about a half a mile into the site where I shoot so I've never chrony'd any loads in winter. It could be done, but thus far I haven't been compelled to go to the lengths necessary to set up and keep a chrony warm.
My just barely sub-sonic "Ruger only" load uses V-N110 lit by GM150M primers, and it performs well in the cold. In my revolvers soft LBT Blue seems to do pretty well down at those temps, and frankly I suspect quite a few others would as well. In the -20 to -40 range, 3 parts sweet yellow beeswax + 1 part Amsoil Saber Professional 2-cycle oil seems to perform quite well. At least I can offer that I get a normal lube star on the muzzle, zero leading, and the bullets go where I point them. Good enough for me. I can foresee this lube becoming my one lube fits all for Alaska temps year-round.
I've taken caribou and moose in sub-zero temps (probably down to around -40 or so) with rifle handloads, but not using cast. Wouldn't be inclined to shoot anything below -40, unless it was a matter of life and death. Coldest I've ever knowingly experienced has been -63...and you still need to go out and tend to animals and critical chores, no matter how cold, but otherwise below -50 I prefer to stay indoors and avoid unnecessary travel because things just start getting weird and stuff breaks more easily, and it's just not very pleasant.
My definitions:
+80 or hotter = "Africa Hot" (fairly rare here, thankfully)
+75 to +80 = "damn hot"
+45 to +75 = "summer"
+30 to +45 = "cool" (spring and fall temps)
+10 to +30 =
extremely warm winter temps (T-shirt weather)
-10 to +10 = "warm" winter temps
-20 to -10 = cool (or "normal") winter temps
-40 to -20 = "cold" (you might actually want to put clothes on to go to the outhouse in the middle of the night, if it's going to more than a quick trip).
-40 and below = "damn cold" (It rarely gets damn cold anymore).
Seems like what's really needed is not an "extreme cold weather lube", but rather a lube for us normal people, which will work good from "cold" winter temps up to "damn hot" summer temps....and a lube that works in "Africa Hot" temps where all you crazy people live.